I used a push scooter in Munich in combination with buses and trains. It was fine for short distances of like ~1.5km or less, going to/from transit stations, but past that distance it just gets fucking annoying. Standing up on a push scooter and constant pushing with your feet just isn't as comfortable as sitting down and pedaling.

Also, the non-inflated rubber wheels I had on the thing were very uncomfortable (and loud) on cobblestone-type roads. Almost infeasible to use, really. But otherwise it was a pretty convenient thing to have.