I did way too much thinking about this today lol

It would be a super small amount of heating unless the acceleration was relativistic, so negligible

The separation effect of the acceleration (centrifuge forces) would also be pretty small at all but very high accelerations

And the amount of damage caused by the acceleration would be a lot smaller without any gas at all-- BUT gas is a byproduct of a large number of our body processes like oxygen uptake, AND that acceleration would still have a meaningful effect on your body's different systems. You would still die of a stroke at pretty small accelerations

Edit: also good call! I totally forgot about the latent heat of vaporization thing being the primary factor