there is a huge difference between accelerating to 100 km/h in 1 or in "a couple" of seconds.

given constant acceleration (which is unlikely, first you are traction limited by the tyres, then the highest acceleration, then slow dropoff), accelerating to 100 in 1 second would mean pulling 2.8g, while for 4 seconds it would only be 0.7g.

I think you’re wrong there. There are snow mobiles that do 0-100 in 1-3 seconds but they are all crazy special built machines like this.

4-6+ seconds is much more typical for a normal unit. Which is similar to normal-ish 200kW sports cars. A bit fast but not breath taking.

A quick google shows snowmobiles are doing 0.5 G vs 3G.

3g on your body, you need a very good grip on that jetski handle...