Something better would be great. She's probably an extreme example, but I think we techy people tend to have a warped view of how comfortable "normal people" are with effective password management.

Same, especially since I don't have a smartphone.

Often times I'll go a week without looking at my phone and by then it has lost its charge so if an app requires a OTP to do something I often need to wait a while before it's charged enough to receive a text.

I do have a Google Voice number but I've mistakenly used my real number for a few services that frequently require SMS confirmations.

If I claim to have forgotten my password, the first idea it has is that I should prove I still have my Security Key

Then it suggests it could send codes to my GMail (which might actually be useful if I have another device signed into that) or to another email address it knows about (it deliberately redacts part of each address in case I am not me)

Then it resorts to suggesting I try passwords I remember using on this account. I don't know what happens if I give it a password I haven't used for a few years, 'pass' means I keep a complete git history of Google passwords but I am reluctant to mess with this

Then it says too bad, it cannot authenticate me.

(Actually, it doesn't send a code to your phone. It either sends a prompt to your phone, OR you can open a buried menu in some app to GET a - essentially TOTP - code.)

While if I lose my SIM card, I'll walk to one of my operator's shops (there's probably one within 1km), show them my ID, and they'll replace the SIM. It's the only digital identifier that I could bootstrap from if I lost access to everything in one go.