Hey, for the password manager we haven't decided on the different integration options, yet. But KeepassXC surely is on one of the top positions. Generally, OpenPGPCard only defines a set of keys for a single identity, we plan to be able to switch identities, but there are also no plans yet how many this will be. For SSH I would recommend using FIDO2 Resident Keys, there you can as of now already have 20+ easily.