I'm running Kubuntu 21.10. Can I run Google Authenticator without needing a cellphone?
If you can obtain the image with the QR code containing the secret, you can achieve the functionality of Google Authenticator with a handful of command-line tools.
Words written above in capitals are variables that you will need to extract from your actual code. To generate tokens, you can invoke
oathtool (from the oathtool package) from the command line, like so:
oathtool --totp=ALGO -b SECRET -d N -s MM
The above assumes tokens are generated in TOTP mode (as most are).
oathtool supports HOTP mode as well, which I am not describing here; generating tokens in that mode is a little more involved, as you need to store the number of times a token has been generated, but is still doable. Look at the relevant manpages for more information.
Google Authenticator specifically uses a phone for the 2-step verification. The second step is a code sent to your phone.
You can choose to "keep it simple":
During sign-in, you can choose not to use 2-Step Verification again on that particular computer. From then on, that computer will only ask for your password when you sign in.
You'll still be covered, because when you or anyone else tries to sign in to your account from another computer, 2-Step Verification will be required.