Let's have your "sudo parted -l" one more time. All disks, all output.
If it is from a mac-mini, say so.
If it is from another system, say so.
Whatever, all disks. All output from each.
Do mot mix gpt with msdos
Do not mix uefi and bios-legacy.
If you take the external disk and put it into another with another mode (msdos or uefi or...) you are also asking for trouble.
You have too many messed up things besides above.
if your swap defined by your fstab of your external is in an internal disk
How is it going to work if you put into another system without that internal disk anymore?
Remove all swap in your fstab first. Remove 'resume' in mkinitcpio.conf and 'mkinitcpio -P' and resume=UUID in /etc/default/grub and 'update-grub'
After that, we'll handle swap. Make everything work fine first without your swap getting in the way.
And no other fstab entry that refer to any internal disk partition.
If your swap is that of that external disk, then it is okay.
If you mix mados and gpt, you will need to reinstall
If you mix uefi and bios-legacy, you will need to reinstall.
If this external disk is set up in (properly) in a system of say gpt/uefi,
Do not put it in another system of msdos/bios-legacy
And never ever update it in that separate system. which is different from the set up system.
You are just doing too many things and you are confusing everyone with output from another system. Whenever you output, say it is from mac-mini or from another system,.
Without solving one thing, do not try to bring up another problem.
So fix in from say mac-mini and then we'll fix another system later. Okay?
First. No fstab entries of any internal disk partition.
Then Remove swap. mkinitcpio and grub. (IF swap is that of internal disk)
Then only this system. No other system.
sudo parted -l