IPD alignment is adjustable on most headsets nowadays. My experience is anecdotal anyway and I fully accept that some people can't handle it.
That said, being on a boat for hours is hardly something we were evolutionarily designed for either, yet no one writes scare mongering articles and posts about that. So you might be doing a disservice with all this worry you're stirring up.
IPD adjustment knobs are there, getting it correctly calibrated for your eyes is still not easy. It takes either a direct messiness with a ruler or a 5-10 minute calibration process in-headset.
And again, motion sickness is by far the least of your worries. My point was "don't just assume nausea is motion sickness". There are other defects that can cause nausea that are not adaptable.
That said, being on a boat for hours is hardly something we were evolutionarily designed for either, yet no one writes scare mongering articles and posts about that. So you might be doing a disservice with all this worry you're stirring up.