I think the article is honestly a little outdated on this point. The last couple of years the adapter market has caught up pretty well.

The UGREEN 8K@60Hz Display Port to HDMI Adapter I have sitting here supports g-sync (and claims support for freesync).

I mean the article is two days old, so perhaps not that outdated. There also seems to be a difference between G-sync, Freesync, and HDMI VRR.