Get LibreELEC to ignore complete physical harddrive?

Hi there!

In the past I only read this forum, when I ran into a problem with a LE-Installation. Thanks for all the help!

But now I ran into a problem issue, I couldn't find the answer to:

I got myself a Dell Wyse 5070. It came preinstalled with Windows 10, which I am going to keep for ... basically everything exept media playback.

For use as a HTPC I installed Generic.x86-64 on an external USB-Drive, and everything is going great so far. At boot i choose which drive to boot.

These are my drives, sda being the internal M2 and sdb the USB-drive.

LibreWYSE:/ # ls -l /dev/disk/by-label
total 0
lrwxrwxrwx    1 root     root            10 Jun 20 19:00 ESP -> ../../sda4
lrwxrwxrwx    1 root     root            10 Jun 20 19:00 OS -> ../../sda5
lrwxrwxrwx    1 root     root            10 Jun 20 19:00 +RECOVERY -> ../../sda3
lrwxrwxrwx    1 root     root            10 Jun 20 19:00 Storage -> ../../sdb2
lrwxrwxrwx    1 root     root            10 Jun 20 19:00 System -> ../../sdb1

Now I would like LibreELEC to completely ignore anything that happens on sda. Not showing it in file- and drive-lists, not reading any files from there and definitely not writing anything to it. Basically I want LE to deny that something like sda has ever existed.

I didn't find any entry in GUI for that and the fstab seems to be empty.

Is there a way to accomplish this?