I have two TV boxes, one is a Raspberry pi 4, the other is a pi 5. I installed KonstaKANG’s android port for the Pi’s. Depending on your familiarity with flashing the Pi’s this video from Explaining Computers offers a way to get Konsta installed through PINN. Once they’re up and running they act just like a cellphone. This remote works really well.
Install f-droid, and/or obtainium, and/or Aurora Store and you can install whatever apps you want on the box.
I don’t personally use Chromecast, so I can’t vouch for that working. Mine is more centered around consuming Jellyfin (jellyfin android tv app), youtube (newpipe), podverse, and Radiodroid
I really liked Kodi, but could never get it to correctly sync across devices so I finally went the android route. I’ve been pretty happy
Feel free to pick my brain if you have more questions
They’ve critiqued themselves on this. None of us are completely pure. At least they have an active matrix channel