If I open up the Camera app that came installed by default on my Librem 5, and point it at a QR code such as to access the menu at a restaurant, the QR code highlights in blue and when I click it the menu opens in the default browser.
Gnome Authenticator exists but I had trouble with it. For websites using generic TOTP 2FA such as GitHub, JetBrains, 1password, and Codeberg, I have a command line solution. I installed oathtool with apt. I have a 2FA folder with my secret keys and a shell script for each site, which generates a 6 digit code based on the needs of that site. For example:
codeberg.sh:
#!/bin/bash
oathtool -b --totp=SHA1 @codeberg.txt
Running the script for the given site outputs an instance of the required 6 digits.
Unfortunately, the Microsoft Authenticator for my work stopping accepted this, because Microsoft are evil and allow IT administrators to require users to do Android/iOS push notifications.
Anyhow, having a command to power my 2FA means I can easily transfer my secure keys and the power to use them into any device, or build a GUI that would display this information, all with relative ease.