I'm writing simple scripts to use them with tampermonkey on various sites using Firefox Nightly for Android(precisely smartphone). These scripts are working with timers, refresh page from time to time, etc, the problem is that scripts stop working when firefox is minimized, or when phone is blocked. Is there any way to force Firefox and Android to keep scripts working, to keep page working as normally but in background?
No. Android can kill any app that isn't in the foreground at any time. If you need reliability for background apps, Android is not the proper OS for you.