I am not there yet, but can you sell those ideas to me? I have heard of them but don't know the advantages they have over Trezor.
Discussion
They're both air gapped. Trezor's not. But I would still skip coldcard (due to closed secure element) and go for DIY Seedsigner instead.
Anyway, don't rush, if you're using Trezor with a passphrase, you're miles ahead of ledger.