If you'd take a passwordless login with FIDO2 (now promoted "Passkeys" by Apple and Google) it would mainly require to use FaceID / Windows Hello / Fingerprint / PIN ... or whatever your devices deem necessary. Could be used on any and cross-device.
I like how tangible passwords are. Even with a password manager I can write them on a piece of paper, store then in a vault and enter them into a new computer. My grandmother understands this process.
The key-based systems are basically magic. Magic that works great as long as you are inside the defined parameters on supported devices. I think it will be years after the "first baked release" before we see relatively user friendly manual backup and restore. Something this is second nature in most password managers.
Yes, availability on all browsers and devices is not yet up to 100%. I hope to see a fast adoption, but agree that it could actually take some time. I use Passkeys on a daily basis for the last ~1.5 years wherever possible and won't go back anytime soon :)