WebAuthn is an UX improvement as well as a security improvement. I sympathize with your point, but in this case it’s easily sellable as the cure to the rest of your list … unless you somehow lose your key.
I don't even think it's realistic to get him to use a smartphone for this, he hates the things.
WebAuthn works great for your Web 3.0 startup but as soon as you're talking about the average user, who is likely decades older than the commenters here, and far less interested in keeping up with these things, and far less patient with the hassles... asking them to carry hardware is a nonstarter for so many.
I don't know anyone using "Hello" but I suppose it's an option. Most Windows users would likely have to use a hardware key though.
That's surprising. As in, the fact that that happens is to be expected from the firmware's point of view - updating the firmware changes the measurements made to the TPM so any secrets can no longer be unlocked. But I would've expected Windows to update the expected measurements before applying the update to prevent that from happening.