Hi we need mobile power supply for an IoT Redboard RP2350
Which options do I have if I have to use batteries or a power bank?
We sell this one that would work well, although you’ll need to use a usb-c cable instead of the included micro-usb unit 
Is there a possibility to buy this in Europe? Germany?
Sure FAQ - SparkFun Electronics , though you may note that most any decent portable battery bank should work