Did your Roku TV decide to strong arm you into giving up your rights or lose your FULLY FUNCTIONING WORKING TV? Because mine did.
It doesn't matter if you only use it as a dumb panel for an Apple TV, Fire stick, or just to play your gaming console. You either agree or get bent.
The thing is 5 years old so that's hardly surprising. I just googled 65 inch monitor and this was the first hit.
Just checked Geizhals and apparently there's none currently, the largest is the HP Omen X, 64.5". Close enough though I'd say. There's 55 monitors 46" and higher but only 7 52" and higher.
At that size I'm obliged to ask if you don't want a projector instead.