What does macOS need?
To understand where these sections come from, you need to understand what macOS is looking for in a disk drive for it to install "properly". macOS put some restrictions on the size and the possibility to even format a partition as HFS+ if some requirements are not fulfilled.
macOS looks for:
- a GPT formatted disk
- a EFI partition:
- FAT32 formatted (not that it matters for it)
- flagged as EFI System Partition (hex: EF00 in gdisk)
- is 200MB at least
- in the same disk where macOS should be installed.
- 60GB of free space
If any of these are in your target disk, you're good to go, if not, that's the point of this guide.