I have to type 25 character random passwords into AppleTV with no mistakes 5-10 times from a remote.
On that note, it's 2022 and I cannot set up an AppleTV in the Home app on a Mac. It's apparently impossible.
1. Devs incorporate an OAuth code based flow. Many apps do this. Passwords should rarely need to exist on a TV device.
2. Paste using the remote app if you have an iPhone.
The first is caused by dev laziness (and possibly better for rare scenarios where there isn't a second device) and the second is perhaps a cost thing (do you have an iphone?)
The typing experience on AppleTV is actively user hostile - the password is masked (you cannot reveal it) so if you even think you've made a mistake in one of your 25 characters, you need to start over.
The second doesn't work for me: we only have Android devices. It's unclear why our 3 MacBooks aren't sufficient for this purpose; I didn't have any suspicion that this would be the case.