Many services offering 2FA, esp. TOTP, will give you a set of backup codes – print/store them separately, safely (using the rule of backups). At the very least, Google does and allows you to view the existing ones and I think regenerate new ones on-demand as long as you can currently securely access your account.

The same can be done with security keys – typically you can add more than one to your account so have at least two and keep one stored safely somewhere.

Sadly, I recently set up an AWS account and, from what I could tell during that period, they support TOTP/hardware keys, but you can seemingly only pick a single 2FA method – so either TOTP or one single hardware key. That’s a service I would have expected better from (or perhaps I am misunderstanding my settings panel where I can’t find a way to add another factor – I am rather new to managing that ecosystem/account).