My PC doesn't even have a microphone.

This is likely something like a FIDO token/passwordless setup of some sort (i.e. Windows Hello).

The thumbprint would just unlock the hardware device, so the thumbprint itself wouldn't need to be transmitted to your credit issuer. This gives you full two factor authentication of your identity because you need the hardware device (something you have) and your biometric (something you are). They also often allow pins (something you know) instead of biometrics as the second factor.

The first thing I thought was "what's the alternative?" If I don't do biometrics on my phone then why would I do it for my credit card? I'm American so I don't have to worry about this yet but it's probably an indicator of what's coming here.

It'd be cool if they had a yubikey integration or some other hardware based solution where you must physically present it.

I might be wrong, but I think they will probably let the OS handle the biometrics offline, which means that they won’t have access to your biometrics, they just work with cryptographic keys. Otherwise it doesn’t make sense, as apps usually don’t have direct access to the fingerprint reader. It will probably be similar to how a passkey works.

In Europe it was relatively smooth though, in my experience. I worked in a shop when it was rolled out. I'm guessing you're American?

That isn't a concern and it shouldn't be. People are responsible for themselves, why should I be inconvenienced because progressive iterative improvements could negatively impact a select few people that are entirely responsible for themselves?

As for hackable, they would not do it unless it was more secure and if it is easier for the consumer what is the problem. Fraud protection is standard here anyway, never heard of someone not getting their money back when someone else uses their account.