I can totally understand the sickness part, have had it too.
The ride with the Michelin PS AS4 is definitely smoother. The 2023.44+ update also helped somewhat - note I have a 2023 MXP but my previous 2023 MX also had the same vibrations.
Having said this, I am trying really hard to live with the car. It is just not a smooth ride and, as you point out, you can be on the smoothest newly paved road and still feel seat vibrations and lots of unwanted steering/yoke feedback, mainly between 30 - 50 mph. I feel nothing with our EQS on the same roads, and don't remember a feeling like this with any of my previous cars (BMW M5s, M3s, M4s and Mercedes AMGs).
The strange thing for me is that the amount of vibration seems to be a variable based on I have no idea what. Weather, rain or clear, hot or cold, have not been able to pinpoint it but it is not the quality of the road. Best way to describe it is that you have a very nervous passenger behind you with their knees touching the back of the seat and they are mildly shaking it every so often.
It is impossible to drive at those speeds with your head resting at the headrest. It feels like wearing some kind of electric head massager at its lowest speed.
Debating everyday with myself what to do next. At this point the only thing I can think of is that this is the car and it is a design flaw and the majority of people who can live with it are just not sensitive to these vibrations.