I heavily use KeePass implementations like KeePass2 and Keepassxc as password managers. It would be interesting if the Seedkeeper card could optionally be integrated into Keepass.

That would be awsome to have such a Keypass integration. But it takes time and connection with their team - not that easy.
At least we could implement an import functionnalities that allow a user to import a .kdbx file into a Seedkeeper. But here again, as the memory size of a Seedkeeper is limited, it can be a mess to select what to import. Anyway, we are thinking about it for the next software release.