I've never tried it myself but the Android TV version of LineageOS can run on some Banani Pis ^1.

Fire TV is Android TV so yes it will also get the update! Unfortunately Amazon rejected the update like they often do so it will take a bit longer before the update is available on the Amazon Appstore.

edit: I just checked and it's live now!

The newer Chromecasts with "Google TV" are just Android TV with a different launcher. If you have a remote control you have Android TV.

First post on Lemmy! (Well technically second because I borked the first one haha)