At least for Duo, you can extract the HOTP secret [1] and use it in any OATH tool, e.g. with the otp extension of pass(1) on GNU/Linux (which uses uses oathtool(1) underneath). You can also do it a more difficult way, e.g. using the Duo app under anbox.

1. https://github.com/simonseo/nyuad-spammer/tree/master/spamme...