Even though snaps show was created in VENV, everything works the same way on bare metal. After you created the new partition of desired size installer brings you to screen which allows to redefine functionality of partition and assign name to folder supposed to be mounted on this partition . In case name of folder is not on the list you can create new folder’s name manually . . . .

Source: LXer – Debian Testing UEFI setup on bare metal via manual partitioning