Is it possible to use Electrum to create a multisig wallet with a trezor and an airgapped coldcard?
I am having the same issue and would prefer to comment but don't have enough reputation.

It seems like this pull request is being reviewed and will add CC multisig integration into electrum.

However, there is currently a coldcard hardware multisig fork of electrum that is available here though several commit behind the main electrum branch. 

I haven't been able to build this fork successfully so hope there is additional work on Cold Card integreation in the near future.