New USB HDD: Please help!

I just want to encrypt the USB HDD so I can give it to my friends. It’s brand new and contains no files as yet.

If you are on Linux, I would just use wipe it completely (I use sudo dd if=/dev/urandom of=/dev/sdX iflag=nocache oflag=direct bs=4096 but you don’t have to), put LUKS(v2) on the ext4 filesystem and ship it off to them.

However , if your friends do not have Linux, then you will have to go exFAT/FAT for cross OS compatibility (out of the box), or NTFS for Windows, or (I think) APFS for mac. OSes have software you can download to read from other filesystems, so I would do research on that as well.

Oh, VeraCrypt is amazing for this as well. Hope this helps.