Did some research and it seems like the best things I could do are 1) use a more gradual easing function (cubic maybe?). 2) Options to turn off / adjust movement speed. 3) Options to change POV.
I also saw a thread that suggested more static UI elements would help. I was going to do that already, but interesting if that helps. I also wonder if the option to use onscreen buttons instead of keyboard helps as well.
Viewing post in The Purple Tower jam comments
I'm no expert, I literally found it out by implementing it and having someone who was watching my stream go "OH THAT MAKES ME FEEL SICK STOP". I changed it so that the turning was just linear, which seem to fix it. Something about the speed up and slow down of the movement doesn't work well for some people, I guess.