There are a ton of headsets beyond the three you mentioned (Glass wasn't a VR anything). Valve, Pico, Pimax, Varjo are a few off the top of my head. Pico 4 would be very competitive against the Quest 3 if they had released it in the US. Presumably the decision not to has a lot of to do with the TikTok stuff. Pimax has several higher end headsets that are very good hardware wise but not the best on the software side. Valve Index is still very popular and there are rumors about a new Valve headset coming soon.