No variable refresh rate support (aka FreeSync in this case) makes 120Hz handhelds completely pointless and without VRR it arguably does more harm than good for gaming specifically vs standard 60Hz panels. 🤷
Hitting 120fps in modern games on handheld class hardware is generally impossible, meaning you'll either just have to run the game at a locked 30/45/60fps w/ V-Sync (making the 120hz display absolutely pointless) OR deal with all the HORRENDOUS screen-tearing that comes with using an unlocked 120Hz capped framerate w/o V-Sync & VRR.
Now I don't blame Zotac for this crappy situation. It's not their fault literally ZERO OLED MANUFACTURERS currently make a handheld/tablet sized 120Hz display w/ VRR. But until that hypothetical display panel DOES actually exist, 120Hz is mostly useless for gaming although ofc it DOES still make all non-gaming interactions/use MUCH smoother & more pleasant.