Hey Fabian!
You can vote for a feature to allow pinning within groups here: Pin filters in filter groups - #4 by Chr1sG
Chris’s workaround seems to be work for in this scenario though!
Except the last part I think isn’t right (@Chr1sG correct me if I’m wrong)
Since it’s an “OR” condition, having this on encompasses all the other groups as well, so when this is enabled, the other conditions have no effect. So there’s no good way to have the “base filter” when the rest are off. I think. Maybe Chris will find a fabulous workaround as always.
Improvements to filters are coming soon though, so I hope this will be part of those improvements!