From what I can see online, Roku TV only supports Miracast. Quest headsets support Chromecast, a competing standard by google.
Miracast is used by systems like Windows to do wireless streaming (my LG TV has Miracast, I can connect my PC to it by wifi).
Chromecast is used by Google's devices, plus things like Nvidia Shield TV (a Roku TV competitor). While my Quest can't cast directly to my TV (because it's Miracast), I can cast from my Quest to my Nvidia Shield which is connected to the TV.
You could probably buy one of the little Chromecast devices that plug into a TV. I bought a few of them just for streaming Quests to TVs for an exhibition.
Although these days Meta recommends not to use Chromecast because it's not fully supported by them (I think they removed it at one point then brought it back).
Most android mobile phones support both Chromecast and Miracast, so that's why Meta recommend casting to their mobile app, then letting the phone do the rest of the casting.