That Proxmox is using grub on UEFI does not change the process?
I#m very unexperienced when it comes to UEFI booting, sorry...
root@Iteanova019pve:~# efibootmgr -v
BootCurrent: 000B
BootOrder: 000B,000A,0004,0009,0008,0007,0006,0000
Boot0000* Integrated NIC 1 Port 1 Partition 1...