It's been years since I've done that. But I still keep a stack of USB sticks that I bought (or got as freebies from conferences) some 8-12 years ago, some of which have enough space for a Windows or Linux ISO to fit.

Create a FAT32 partition on your SSD/HDD, unpack your .iso there, and you should be able to boot from it. You typically don't have to mark it as an ESP partition. It works on most motherboards, but not all.