That’s a problem with any software. If you keep updating the OS eventually some programs are going to stop working. This is true for any OS: Linux, Unix, MacOS, Windows, Android, iOS, etc. Eventually something the program relies on no longer exists or works in a way the program can’t handle.

I don’t see any good solutions. Options I see:

• Keep an old device to have older versions of Android, or whatever, so the software you need will still work. Sucks to have to find the specific device for whatever your trying to do. Also, don’t know how easy they’d be to replace/fix if they broke.
• OSes no longer remove any functionality, only add-on to. This causes bloat and performance problems at the least. Not to mention would be incredibly hard to maintain on any long term scale.
• Have some way to emulate old devices/OSes so you can run instances that work with your software. IDK how well this would work with multiple instances. Probably can’t do this on your phone so you’d need a different dedicated device. Not to mention I’m not sure how many different instances you can emulate at once before you start having problems.

Everything seems to have drawbacks. That’s one advantage of devices having dedicated hardware, and software that doesn’t rely on outside hardware/services. Updates won’t kill it and they can’t take it away from you. Though, they still don’t have to support the hardware forever so it gets harder and harder to fix as time goes on, if it’s even user fixable to begin with.