There are still handshake issues with that.

There IS a workaround consumers can do. It involves flashing a REALLY sketchy firmware to one of the mainstream dongles. And it still isn't true HDMI 2.1. It just gets you VRR and enough HDR that I don't know the difference.

But probably not something a company like Valve wants to actively sell. Expect hundreds of variants on aliexpress but your country may vary as to whether that is cost effective to purchase.