b) most annoyingly, some android TV devices (e.g., nvidia shield, ccwgtv) use renegotiation instead of VRR for framerate matching. The FO48U supports VRR from 48 to 120Hz, which is more than enough to do framerate matching even with blackframe insertion for all desired framerates, but many android TV devices renegotiate instead. That means pressing play on Netflix takes 7 seconds until it starts. Quite annoying.
Still, it's preferable over TVs with shitty built-in OSes.
What's made this a bit more tolerable for me is to set the source's (Apple TV, but it does the same thing) frame rate, HDR mode etc. to the one most likely to be used by the majority of the content you're planning to watch.
But I'd take a few seconds of renegotiation over frame rate juddering any day, at least for film content (maybe not so much for shorter Youtube clips).
Personally I'm hoping nvidia will release a new nvidia shield androidtv box soon with support for VRR, as my AV receiver and the FO48U support VRR without any issues. That'd allow perfectly smooth watching experience for all content, which would be awesome.
Apparently 55" monitors do exist, a quick search yields Dell and Samsung for $2~3K. I don't know about TVs, but similarly sized ones seem available for half or even quarter of that price.