Open Source Mobile Os

I am trying to figure out:

Is there a Mobile os that is functioning, however basically, that I can install on my $20 android phone?

The model is A574BL, it has like 1.7 gig of ram.

From what I can tell from my internet searches, I cannot. As far as I can tell something about phones makes them very distinct and os need device specific information.

All the information I find online is speaking phone software lingo or Linux lingo and I can’t understand it. I understand javascript fully.

Could anyone break the open source Mobile os landscape down for me in laymen’s terms?