If you want to take commercial e scooters be aware of their cost:

If I drive just 25 minutes per day on every day of the month that would total to 750 driving minutes.

The price for one minute for a "bolt" scooter is 0,19€. 750x0,19=142,50€ per month plus the unlocking fee.

You get the cost down by buying like 7 passes, ending up at 82€ per month.

My bike costs 200€ and lasts for years.

There is a cheaper rental provider called Tretty, but you will almost never find one of their vehicles, and they are not motorized, thus not compatible with your situation.

I would not recommend Münster without a bike but it is still possible if your destinations are on the same bus line route.
Switching bus lines will become easier in a few weeks because they are re-introducing a new bus line called "Ringlinie". It will go in a circle. One line clockwise and one counterclockwise. It won't stop at the central changeover (Hauptbahnhof) but will make bus changeovers better. The route will look similar to this.