I have two TVs running completely off arch. One is a Lenovo Tiny PC, the other is a home server I built.

The frontend for both is just the normal arch desktop, running cinnamon with just some visual customizations. Each one has autologin, and on boot they open to the desktop with icons for Plex and a web browser that has shortcuts to all our streaming services on its home page. I also had Kodi running on them, which is handy because you can boot into it, but everything I was using it for Plex did better. I don't bother with a remote, I just use a Bluetooth mouse.

The little PC in my bedroom is basically just a frontend. The bigger system in my living room is a frontend but also runs a Plex server, some servarr apps, plus a bunch of unrelated services. My wife is not super tech-savvy but it's intuitive enough for her to figure out the interface.

My biggest friction point is my one streaming sports app that won't save my login longer than 7 days, so I have to keep logging in to it but I don't have a keyboard attached. I use a virtual keyboard as a workaround but it takes forever to peck out my login that way, and the app will log me out in the middle of a game if my login expires. More annoying than anything.

I'm not familiar with Waydroid or Big Screen, and I don't use either of these systems for gaming, so I don't have any advice there.