Also, if you do, make sure your tails instance is kept up to date.

There's one more thing about this which that you might want to beware also, which is Electrum does not use the same seed derivation scheme as most other wallets, which I think causes you to get a mismatched descriptor messsge if you upload another wallet's descriptor in the setup wizard. I think you can change the derivation path on setup, but I cannot remember and I wouldn't trust me anyway.

I'd keep the Tails instance up to date through the instructions on https://tails.net/doc/upgrade/, though it may be less critical for an instance which is never connected to the internet. Something to keep up with for sure though (much like firmware updates on HWWs).

The Electrum seed derivation is a real footgun and this is indeed the kind of thing I hoped to uncover through this post. I've heard previously of Electrum's non-standardness so that would be something to thoroughly explore and test out first, before making a multisig with it. Perhaps using Sparrow on the persistent storage would be just as good, and then I'd be using a wallet that I'm more familiar with? Wasabi has also been mentioned below.