Certified OpenPGP-encryption after release of Thunderbird 78

[karel-v_g at tutanota.com]

Hello!
I am required to use certified encryption for mails by my supervising authorities and good practise.
Because of this I have been using a combination of Thunderbird, Enigmail and Gpg4Win, as the latter one is certified by German BSI.
With the approaching release of Thunderbird 78 Gpg4Win and Enigmail won't be available any longer and the new OpenPGP-implementation of Thunderbird won't be certified to the best of my knowledge.

I am aware this might be slightly OT for this list, but are there any suggestions what can be done to keep up a certified encrypted mail communication?
I am afraid Outlook which should work easily with Gpg4Win is not an option.
Thanks for suggestions and help!
Karel