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.
@Niels
@lemmy.ml