Metis theme is now running on bootstrap5
The ways how to customize admin area (That ones I found)
The site was updated to 2.3.1 stable version
Using WP for areas when e107 fails and e107 for adminstration custom things
Snow White theme is theme inspired efiction theme with bootstrap5 support
Somerbrise theme is theme inspired efiction theme with bootstrap5 support
Artemis theme is e107 bootstrap5 theme based on Soft UI Design Free by Creative Tim.