Looks like it can do 4k 120hz, but since it's limited to HDMI 2.0 it will have to rely on 4:2:0 chroma subsampling to get there. Unfortunately the lack of HDMI 2.1 might be down to politics, the RDNA3 GPU they're using should support it in hardware, but the HDMI Forum has blocked AMD from releasing an open source HDMI 2.1 implementation.
https://arstechnica.com/gadgets/2024/02/hdmi-forum-to-amd-no...
There are two kinds of DP to HDMI adapters. The passive ones are like you said, they need special support on the GPU (these ports are usually labelled as DP++), IIRC they only do some voltage level shifting. The active ones work on any DP port (they don't need AFAIK any special support on the GPU), and they do the full protocol conversion.
Club 3D active adapter: https://www.amazon.com/Club-3D-DisplayPort1-4-Adapter-CAC-10...
I’m using the Club3D active adapter, which is the only one I found in reviews to reliably work. And it does, 0 problems whatsoever.
It seems to me the wireless is pretty important. I have an MQ3 and I have the link cable. For software development I pretty much have to plug the MQ3 into my PC and it is not so bad to wander around the living room looking in a Mars boulder from all sides and such.
For games and apps that involve moving around, particularly things like Beat Saber or Supernatural the standalone headset has a huge advantage of having no cable. If I have a choice between buying a game on Steam or the MQ3 store I'm likely to buy the MQ3 game because of the convenience and freedom of standalone. A really good wireless link changes that.
I'm talking about the Steam Machine here. In theory you could pipe 4k120 to the headset assuming there's enough wireless bandwidth, yeah.