I wanted an almost invisible mount for an Apple AirTag for the e-scooter. The best option here seems to me to be the existing reflectors. I'm not quite sure if these fit the different models in the EU or other countries. I only had a Xiaomi Scooter 1S from Germany to test. There are 2 files to download, one for EU models and one for old M365 models (not tested).
Materials needed
a pair of longer M3 screws, probably M3*12 and M3*14 will work
some Loctite, to secure the new screws. The original ones are also secured with it
Mounting
to mount, remove the existing rear cover on the side with the disc brake, just press with a thin metal pin in the hole in the plastic, then the reflector should come out of the holder. (See Picture 1 below)
now loosen the two M3 screws and remove the black plastic part, inside are two cross pins that must be removed, because there comes the AirTag. (See Picture 2 below)
now simply mount again with the printed AirTag holder and the longer M3 screws.