Comment 88 for bug 1886148

I tested also with plain extraction from the current Lubuntu Groovy iso file to a FAT32 partition with what I think are the correct flags

$ LANG=C sudo parted /dev/sdc p
Model: OCZ-AGIL ITY3 (scsi)
Disk /dev/sdc: 60,0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number Start End Size Type File system Flags
 1 1049kB 60,0GB 60,0GB primary fat32 boot, esp

I tried to boot in UEFI mode, but it did not work :-(

The same method works with Lubuntu 20.04.1 LTS (I tested right now just to be sure).

-o-

I loop mounted the iso file and used rsync to copy to the pendrive's partition mounted at /mnt/sd1:

sudo rsync -r --info=progress2 /mnt/lp1/ /mnt/sd1

Then I flushed the buffers and unmounted /mnt/lp1/ and /mnt/sd1.