Is there a good community for sideloading apps to TVs? And/or something like custom roms on phones?

I have a Samsung that seems to be Samung’s closed garden of apps rather than Android proper. They let me down on some promised features, eg Google Voice Assistant (I know, I know, sacrificing security and privacy, but I already have a Google Home listening in elsewhere) that were released in UK but bizarrely they didn’t bother with Ireland despite nearly every requirement being identical. I mean Christ, if my parent’s ancient TV can play Crossy Road why can’t my relatively recent one?

I also have an idle Raspberry Pi that could act as Android box but the motivation isn’t there when my TV is mostly just my kids going between Disney Plus and the Nintendo Switch.