Interesting. I like the strategy, currently I am simply migrating from a ledger that I no longer trust to a multi-sig air gap solution built from a raspberry pi zero. With open source Python code.
Discussion
Multi-vendor-multi-sig is probably the most secure you can get but seedsigner being one of the signing devices is already a great choice I think. I saw they made advances with reproducibility but are not there yet. But even as a black box, it can do little evil due to the way it works.
As I recall that was mentioned in the seedsigner document.
But what are you referring to WRT reproducibility on the seedsigner side?
Thanks for the thread! I can assume you are the Giszmo in those posts. Nice to know I am talking to some knowledgeable folks!