Legacy option in BIOS not doing anything

Been trying to install a 32-bit OS using bootable USB or SD card. Set boot option to “Legacy” in bios. But nomatter what, there is never any device recognized as a bootable disk.

Maybe some other (hidden) bios setting must be tweeked for this.

It’s frustrating as it’s nice it has the RS232 port, which is a legacy interface and the software I need it for, needs 32-bit install.

Anyone every had any luck?