For me it’s the paranoia surrounding webcams. People outright refuse to own one and I understand, until they go on and on about how they’re being spied. Here’s the secret - unplug the damn thing when you think you won’t use it or haven’t used it in a while.
They, whoever it is, can’t really spy on you on something that’s already off and unplugged!
I expect that all smart TVs have a web browser, so the first two should always work. Be aware though that while piped is more usable (imho), it currently does not work anywhere, because it did not yet implement a fix for google’s blocking that invidious did a week or so ago.
If FireTVs are android TVs, you should be able to install the android apps too, in a way or another.