My last Pimax check has been just 10 days ago or so. Unless Pimax have changed their software pipeline since then, the guide is still valid.
Edit: I think the SteamVR resolution manual override is called differently now, I’ll look into that. Apart from that everything should still be set as described in the guide.
Gsync/VRR would have to be supported by headset manufacturers, that’s nothing that can be implemented by application developers. vorpX has a custom ‘timewarp’ mechanism though that can create intermediate frames. While not really related technically that also serves the purpose of keeping things smooth at low framerates.