Those would be huge factors in calculating in-game speed. You would also have to take into account elevation changes which would effect speed differently for an inline skater compared to a biker.
Without a good formula and a baseline of power for inline skating this request will never get off the ground. I am try to assist you in letting you know what would need to be done as far as this requests goes. You will need to come up with a lot more data.
Is there a way to measure power for inline skating. That would be a good starting point. You would also need aero, rolling resistance, how inclines and declines effect speed and many more variables.
You can use this as a guide to get you started: How Does Zwift Determine My Speed?
So far this request is very thin in the details department.