I just went looking myself. German Amazon has a few options. This one seems promising: https://www.amazon.de/dp/B06XHPXSSQ
Particularly because of discussions like this: https://www.amazon.de/Bis-glycinat-Hochdosiert-Bioverf%C3%BC...
Particularly because of discussions like this: https://www.amazon.de/Bis-glycinat-Hochdosiert-Bioverf%C3%BC...