You missed the Android mobile phones app 😢
But what Android TV are you thinking of? Philips, perhaps, without Now whereas Sony have it?
I guess that’s just another form of S/P DIF(f) 😛
I have the mobile app and know I can cast it but that is not the same as having a native Android TV app. Using the phone app also takes up an extra device.
To avoid casting taking up two devices, start the programme before casting it. Then it only takes up the one device that being able to watch Now native on the TV would take up.
I have the faint annoyance that our 2020 LG TVs don’t have All4; we use Roku Express devices to get over this. Only one device either way, but it takes up an HDMI input on each TV that we might like back 😢
I have a theory, backed up by no evidence whatsoever, that Sony contributed to the Android Now app that it uses, such that Now are not free to make it generally available as an Android TV app, for technical and/or commercial reasons.