I would like to know if there is a good open source project that let's me run a copy of a game on my phone without crashing or bugging out after a day or two, nothing on the app store works well enough. I just want to enjoy multiple accounts on an old 32bit mmorpg from 2013-2014.
Unlikely. I've used this with moderate success when I needed to run two Discord accounts: https://play.google.com/store/apps/details?id=com.oasisfeng.island
But I think it partially just uses the builtin Android profiles functionality.