How to install an UEFI-based ISO (bootable with DVD) on an USB flash?

I have an UEFI-based ISO file for a tool on windows (This tool is NOT a WinOS but a separate utility tool).
If I burn this ISO onto a DVD and boot it on an UEFI computer (without Secure Boot) everything works.

However If I put this ISO with e.g. Rufus onto an USB flash drive then the USB flash drive does not boot and show an error message:

"Could not locate 'EFI\boot\bootx64.efi': Not found

Yes, the file and the directory is missing.

After a long search I found a hint:
Surprisingly a DVD-bootable ISO is NOT automatically bootable from USB flash drive due to different handling of Bootmanager.

Interesting. I have not expected that.

Now my problem is:

Can I convert this only-on-DVD-bootable ISO to a bootable-from-USB-flash-drive ISO?

Alternatively it would be acceptable to create at first an UEFI-bootable USB flash drive and extract (which?) tool files out of the ISO onto this USB flash drive. I guess I have to declare (where?) what program should be started during USB flash drive boot.

Any suggestions?

E.g.Ventoy does not help.

It must be a solution which prepares the USB flash drive for simple UEFI boot and let me add (before or afterwards) an additional tool.

Peter