And then there are UI/UX constraints. The Venn diagram of "knows how to use SMS", "knows how to use 2FA" and "knows how to use yubikey etc" does not have a lot of overlap outside a tech audience.

They used to offer an $18 yubikey, but the cheapest one today seems to be $25. So a bit better than $40 but still way more than say a house key costs

The FIDO2/webauthn ones (the Security Key series) are $25 for USB A or $29 for USB C. You can't use them for storing OAUTH keys, they're not smart card compatible, they can't store your PGP keys, and can't create one-time passwords or store a static password securely... but they are cheaper.