In case you haven't tried, the 2 biggest "vr hacks" for motion sickness are:

Have a small circular rug that's a different texture than the ground its on, so you can feel when you step off of it.

And have a single, small, directional fan aimed at you (not overhead.)

Those 2 help keep you grounded and oriented without taking you out of immersion.

But, some games just suck and the locomotion isn't smooth, and can't be saved.