I know of a 4010 E-Loco custom which has one (or 2?) motor of LGB of this size you posted in the ebay pics.
This LGB motor is smaller than the Playmobil-transformer-motor. I think, it has no weights in it.
You can put it in any loco of Playmobil. But... not easy (not plug and play). You have to fix it e.g. with screws.
But..., what will you win with a LGB motor (it is ~four times as expensive as a Playmobil motor)??
You think, it has more power than a Playmobil motor?