I just got a msi pro z790-p motherboard and saw renehoj say that you could it was possible to use the flash rom button and usb port to flash dasharo on this post:
I’m new to bios software since it’s very niche, I can’t find a place to download the rom but I’ve heard it can be downloaded with a pro subscription or built from source. I’m fine with any option not including money.
How might i find a rom to do it this way or is there a method just as simple?
It seems you answered your own question. If what you heard is correct and you don’t want to spend any money then you need to build from source.
If you don’t know much about bios then I’d guess you don’t have much experience building from source. Personally I wouldn’t build it from source and use that to flash BIOS. I’m happy to pay Dasharo for their work.
Nevertheless, here’s the link to dasharo build instructions