Freesync Premium Works With HB0801S !
Ignore those Reddit posts that reported HB0801S of not working with Freesync/VRR, those could be outdated posts.
I hereby confirm HB0801S works well with my TV which supports Freesync Premium. I have my game capped at 30fps which is essentially out of my TV refresh rate range of 48-144hz, but Freesynce Premium with its LFC feature works wonder here by eliminating tearing and gameplay actually feels smooth for a 30fps standard. Really glad that it works (was so worried with all the hit & miss posts about it over Reddit).
Make sure you are using HDMI 2.1 cable on the right TV port that supports HDMI 2.1, also make sure your TV Freesync option is ON, and Windows display setting refresh rate is set to 120hz. Also worth checking the in-game refresh rate setting (if any) is set at 120hz.