I recently noticed that Google Authenticator (and indeed Microsoft Authenticator) can be used with the TOTP method in Advanced Authentication to provide access to Filr

A video of it working is at https://filr.microfocus.com/filr/public-link/file-download/02b982857b2c22fc017ddd520383447d/182468/5050053658468807978/googleauth.mp4

Is this what you were looking for?

regarding "... Filr does not currently support third party Multi Factor solutions.", I remember AA can forward the auth request to 3th party solutions so I guess that would work right?

Multifactor authentication for eksternal users is very big wish on our part. I know this could be a challenge according to the way Filr handles eksternal users. If anyone has a soloution to this - please send us i that direction 

I recently came across a customer who was using Microsoft Azure Proxy with Multi Factor authentication to access Filr and Content Editor.  So this can be done to some extent outside Filr.

There is a MultiFactor authentication entitlement with Filr Advanced.  This is delivered with Advanced Authentication Limited with 4 methods (SMS OTP, Email OTP, TOTP and Radius) so this can be implemented with no additional license cost. 

However Filr does not currently support third party Multi Factor solutions.