I use Clipious, an Android client for Invidious, on my phone. I selfhost my own Indivious instance so this is perfect in that my phone never connects to YouTube directly, and I can save all my subscriptions in one place without a YouTube account.
On my Android TV I use Smart Tube Next. If I really need to cast, I also have YouTube ReVanced on my phone for just that, but I barely use it.
As soon as Clipious gets a proper Android TV interface, I’ll be set, as both devices can just connect to Invidious and let it do all the work.