I didn't invested too much time into hardware keys but requiring additional software on other PCs, still is a no-go for me. With my current setup, I only need my smartphone and I always carry it around.

For business use, this is a whole different topic. With a proper setup, all machines would require the software and you shouldn't access these accounts outside from company devices. Its also an expense which the company must carry and its easier for them to handle backups. Also in that Setup, you can have SSO/LDAP, where you can physically proof that you are you and requesting resetting the MFA. With an online service, they usually require a weak proof, like just the access to an email account.

I just needed to think of the scene from the Simpsons, where Mr. Burns and Smithers go all through the security checks and in the end, there is a flimsy open backdoor, where a stray dog entered the room. All security in the front doesn't matter, if the backdoor is not secure at all and until the backdoor is that unsecure, I'm not willing to add money and time, to make the front door more secure.