A standalone solution is a Wyze camera. about $2. It has no fees (unless you want advanced features), and has a decent app for viewing the feed. It's works well and you can simply unplug it when you're not printing. As a bonus, you can set it up with motion detection as a security cam if you leave the house. I'm not a fan of externally accessible internet things normally but in this instance I make an exception. I do also have a camera setup with my Raspberry Pi, but it's such a terrible quality camera that for smaller prints it does not work very well.
USB cameras are hard to come by because of all the work at home stuff. For a while they were unavailable pretty anywhere.
Tony