How to use Ventoy and use Memtest86 V7.5 Free Edition the only UEFI compatible version for Ventoy.(Update: nope newer versions can also run .img and more file types)
Source: https://libredd.it/r/linux/comments/h8u1dx/ventoy_a_new_bootable_usb_solution/
https://web.archive.org/web/20180714021704/https://www.memtest86.com/download.htm
The actual link
https://web.archive.org/web/20180714021704/https://www.memtest86.com/downloads/memtest86-iso.zip
Yep, this one works, :) just extract the zip and copy and paste it on the latest Ventoy. And you are good to go cheers :)
Update:
A buddy of mine told me that the current ventoy version(Ventoy 1.0.54 release) can also boot and .img and that even the current memtest version( memtest86 free Version 9.3 Build 1000) would boot. So this article is only for historical references :)
I also tried it, it works :)