I recently asked questions about HDR & automatic refreshrate switching for a linux HTPC, and the advice in the end was just to find whatever distro already has it all precofigured (and conflcting advice whether i'd need Wayland or X)... i was kind of amazed how poorly supported it appeared to be.
So yeah, if steam is like "yeah, we won't try to venture into that swamp", can't say i blame them after having dared to ask how to get it to work myself.