After multiple attempts, I have not been able to set up the external
memory card as internal storage or as default storage location.
Since it is apparently not possible to use apps to move installed
programs onto the storage card (no root access?!)
the only option left is to use the external memory card as internal storage.
but it seems there is no option to format as internal storage
Thanks for any help!
The option to format an SD card as internal storage has been (at least temporarily) removed by /e/ developers because this format has kept causing grave issues for users under Android 10 (photos taken not being saved etc.).
For the time being, the SD card can only be set up as external/portable storage. This does not allow to move apps to the SD card. I recommend you move bigger batches of files (photos, videos, music) to the SD card manually (use the “Files” app for this).
Thank you for your reply!