Import from other app - beemdevelopment/Aegis GitHub Wiki
Per https://github.com/beemdevelopment/Aegis/issues/1110#issuecomment-1467570391
In the initial setup screen, you can only import Aegis vault exports/backups. If you want to import from a different app, go through the setup process first and then go to Settings -> Import & Export.
At least with AndOTP, you can indeed import an encrypted export, just provide the password