Update from the article:
Update: June 29, 2023
Sarah Vasquez, the Senior Manager, Communication at Mozilla, told Good e-Reader in an exclusive statement, “Kobo is aiming to update the Pocket login on their e-readers to support Firefox accounts. The exact timing is to be determined. However, Pocket’s existing Kobo users will not be affected nor lose access to their accounts. Note that new Pocket accounts created after August 15th may not have access to the existing Pocket login option, depending on when Kobo support becomes available. Kobo users can continue using Pocket on their iOS or Android device or use Pocket’s website.”
So it's just a matter of updating the login screen to support Firefox accounts/2FA, and Kobo is planning to release an update at some point.