I'm finding the Ephermal Seed function on the Coldcard to be extremely useful.
One can use this function to recover a private key (passphrases can be used), do what you gotta do (sign transaction, create XPUB etc.) and the key would be wiped from the memory when the Coldcard is tuned off.
One can have multiple cold storage wallets, but all you need is just one Coldcard.