Nitroglycerin is added to tame nitrocellulose's ludicrous pressure exponent to make practical rocket propellants. NC on its own (single base) exhibits a pressure sensitivity that’s normally way too high for rocket applications ie. it will burn quite slowly under 1 atm but fast enough to be a useful *gun* propellant under pressure. Where this is important to igniters/starters is that if your system is dual compound and your (inner) primary mix is NC binded, then you want your secondary coating to be “forgiving” (flexible or weak etc) enough as to not confine the primary compound too much otherwise permitting its pressure to rise beyond a certain threshold or the primary compound might “pop” on you ie. burn too quickly to ignite the secondary properly. The same can occur with mono-compound igniter/starters that are NC based in that if the head is too large, the inner compound exposed to the electrical bridge can over-pressurize and produce more of a pop than a complete burn of all the compound.
TP
There is no problem using double-base. The NG det rate is just slightly greater than NC, and it makes a good solvent for NC for powder manufacture. I've seen zero difference for igniters using NC lacquer made with single-base (NC-only; I use IMR-3031) or double-base, which usually contain between 15-35% NG, depending. And in fireworking, both are used for binders when making dragon eggs/crackle, and both work well, though some swear they see improved ignition with double-base (it's a strobe burning effect). What is an important factor in smokeless selection for NC lacquer is that you want the thin fast-burning wafers in shotshell-reloading powder instead of the hard extruded pellets (slower burning) designed for magnum rifle cartridges. The wafers go into solution after about 5 minutes of shaking. I use Hodgdon's International, with green & orange wafers that dissolve to give a pleasing beige lacquer instead of the typical black of most powders. The common extruded pellets are a pain to dissolve, often requiring shaking every 30 min, sometimes over the course of several days. All contain a preservative, mandatory for any NC solution because unprotected NC loves to lose its nitrate groups as nitrogen oxides (that react with/dissolve in atmospheric water to form caustic and highly reactive nitric acid) with storage--usually it's diphenylamine, and it works well, both in powder and solution. For reproducibility in making the standard 10% solution, your calculations should be w/w and account for acetone's lower specific gravity (0.785). Remember that acetone is particularly hygroscopic, so protect it from atmospheric moisture or it'll absorb an unlimited amount of water. For a binder of pyro stars, this is not so much an issue; eventually the water will evaporate. But for metal wiring, moisture + oxidizers = corrosion and can cause device failure with long-term storage. If using dollar store fingernail polish remover, be certain that it says 100% acetone. Still, it's from China, and that's no guarantee. Moisture absorbing beads are available, but some might consider that overkill. Non-hygroscopic MEK (methyl ethyl ketone) is available at HD etc., and evaporates slower than acetone; can use alone or in a mix with acetone to adjust drying times. With dipping, one generally wants quick drying time. Solvent can be added back if it evaporates out of your pyrogen slurry too quickly. Once dissolved in lacquer, NG in double- and triple-base (the third chem is nitroguanidine) is easily absorbed through the skin and can give you a "dynamite headache" if you don't use appropriate caution (and gloves).
Ping-pong balls (old style celluloid) are still available but you're better off buying a known brand that others have used. Celluloid is simply low-nitration NC (mostly dinitrocellulose instead of the trinitrocellulose in smokeless) that is dissolved and polymerized with camphor. They will have a distinct camphor (mothbally) smell, particularly if cut open or punctured. And they will burn with a vigorous yet controlled orange flame that emits essentially zero smoke and leaves very little ash. Plastic PP balls are not considered hazardous, so manufacturers don't need to disclose the polymer used, though polystyrene, cellulose acetate, and polyethlylene terephtalate, and ABS (acrylonitrile butadiene styrene) are likely candidates. All burn but burn like crap. Nobody wants to smell burning plastic (ahem, folks using Testor's paint...), and it produces a suboptimal burn with any pyrogen. And PP balls are less than 3g each, so there's that...
NC guitar lacquer is available from Amazon, but it's rather pricey at around $25/quart + shipping. Mohawk/Behlen (I think product #6011, or close....EDIT: Product #M610-1405, pricing was correct at $25) is also proven. It is decently flammable and probably is closer to celluloid than smokeless in terms of nitration level. And it contains various other solid components and a mixed-solvent (that doesn't evaporate quite as quickly as pure acetone). I have used it for binding dragon eggs to good effect, but because of uncertain additional components, would never use it with certain reactive pyrogens for dipping. Might work great, but just never tried...
https://www.amazon.com/Mohawk-Finishing-Classic-Instrument-M610-1406/dp/B07PG9Z64V/ref=sr_1_1?crid=2828O0F0PHBAT&dchild=1&keywords=behlen+mohawk+string+instrument+lacquer&qid=1617741233&sprefix=behlens+mohaw,aps,100&sr=8-1 . The Colortone lacquer that Mike H provided above costs $41/quart.
Some fingernail polishes are NC-based (forms a nice durable covering on nails, guitars, and wire alike), and will generally list this ingredient if they contain it (legal requirement due to flammability). Unsure what NC concentration, nitration level, and ancillary chems/pigments. Yeah sure, only a buck at the dollar store, but I don't ever plan to experiment with it.
NC-based model airplane "dope" is still available, reasonably flammable, but astronomical in pricing.
Pure NC and NC lacquers for fireworking are available from some vendors. The pure NC ships wet by law due to flammability. It doesn't have stabilizers included, so that's an issue. Unopened pound still in my freezer under some hams, so never been tested... They claim it's 12.5% nitration, but would need to estimate myself with a burn test--I would be surprised if this claim was true. By contrast, the NC in smokeless powder is probably approaching 13.5% nitration, the theoretical maximum. The lacquers usually contain stabilizers. The one vendor that probably still sells this is entirely unreliable (sorry Firefox, you are horrible), and will be happy to take your money and forget you exist, then ghost you completely when you try to get an update. They received a super-punitive injunction for selling M-80 kits over a decade ago. Their temporary injunction expired but CPSC/DOT didn't appreciate that the Purringtons took this to mean they could resume selling M-80 kits, which they did. Not smart. Their injunction is now permanent and put a serious kibosh on their business, from which they have not and probably never will recover. Avoid at all costs.
Trying to extract usable quantities of NG from angina meds is a fool's errand. Milligram quantities per tablet, patch, or spray dose. Expensive. Many of the binders/carrier molecules are burn inhibitors (silicon dioxide, aka sand, anybody?) with variable solubility in acetone or MEK. Not recommended. And NG is an oily liquid that will never dry to a hard shell like NC; it's fine in combination (double-base) but not alone for dipping/binder purposes.