Just found an older Galaxy S5 and put Rocket Track app on it and it works great. A little double sided tape to the eggfinder receiver and I'm set. Kind of looks like the first cell phone I owned, lol.
Those old Android an Apple phones make great trackers out in the field, if you're using a navigation app that doesn't require Internet access. You can pick one up for $50 or less.
As noted in your other thread, you need to sideload the Rocket Track app, but it doesn't work with newer Android versions, so you need an older phone / Android OS