booting UEFI from Legacy (grub4Dos) thumbdrive (SOLUTION BEING TESTED NOW)

[cobaka]

G'day all!

Is it possible to boot Puppy OS with a boot-strap configured with GRUB for DOS in a UEFI PC or must I install a UEFI bootloader?
(-Later I got some suggestions - about this. Will advise after test are complete. Computer of interest is at a friend's place on the other side of town - so I can't test immediately. Thanks to all. -)

Context: Until now, I used only Grub-4-DOS as a bootloader.
Never failed, but now I'm on a Gigabyte mobo running Windows (probaby) 7 (but maybe 10)
Earlier today I installed various Pups on a thumb drive and booted each one (in turn). -> success.
Now I'm at a friend's place, on the computer mentioned above and trying to get past the BIOS boot menu.
I see only UEFI options.

Suggestions?

cobaka

Added later: Boot partition is (of course) FAT32 - about 64MiB
Other partitions ext3. OS files (puppy) are on sda3 - ext3. Maybe 160GiB
Lots of Puppies - Slack 32/64, Fossa 64, uPupBB 32/64 and all booting from DeskPro (or maybe ProDesk 600).
On the desk-pro Puppy is installed on the HDD, but all the previously mentioned boot from a USB thumb drive. (First time I installed more than one Puppy on a storage device).

[bigpup]

In the computers UEFI settings boot section.

You probably need to Enable legacy boot or CSM. (depends on age of UEFI what they call it)

This will make it operate like legacy bios.

CSM offers backward compatibility by booting the machine as if you were running a legacy BIOS system.

It also allows you to use older operating systems that don’t support UEFI. You create the legacy BIOS compatibility by emulating a BIOS environment that’s compatible with your current operating system.

If your computer is relatively new and came with Windows pre-installed, CSM would have most likely been disabled by default.

You don’t need to enable it unless you want to install an older operating system that doesn’t support UEFI – or if you’re trying to boot from an old storage drive that you recently hooked up, that already has an OS installed, for that matter.

[bigpup]

If you are trying to install Puppy alongside Windows on the internal drive.

The Lick installer is designed specifically to do that and make a boot loader that will work with both.
https://github.com/noryb009/lick

[thinkpadfreak]

Is it possible to boot Puppy OS with a boot-strap configured with GRUB for DOS in a UEFI PC or must I install a UEFI bootloader?

If you would like to create a usb stick ready for both a uefi PC and a legacy bios PC, grub2config by shinobar or frugalpup by gyrog will do the job.
They install both boot loaders (uefi and mbr) by default.