It is not necessary but still better to run both online discard and batched fstrim. from man:
Also, a device may ignore the TRIM command if the range is too small, so running a batch discard has a greater probability of actually discarding the blocks.
Filesystem permissions
For many apps it is not an issue and provides additional security but in other cases it’s very annoying and not trivial to fix.
Example1: opening a .docx from Thunderbird flatpak with OnlyOffice flatpak does not work out of the box.
Example2: mpv and VLC flatpaks work well for local files, but fail to open network shares from Dolphin.
I think a possible solution would be runtime permission dialogs when denied access.