Hello there, Superfury!
I've been looking for a good DOS emulator for the PSP for a while, so I was really glad to stumble upon your project. However, I couldn't get it to boot on my PSP 1000 - it runs out of memory. Perhaps it is incompatible with this model?
I also tried to get it to work on the PPSSPP emulator, by setting it to emulate a PSP 2000, which has double the RAM. It would boot in this case, but even then, I couldn't get it to reach the BIOS - all it would do was let me change the internal BIOS settings. I also tried some older builds you posted on Vogons, but the result is the same (except, it won't even show the internal BIOS page).
I tried to stick with the most basic tweaks to the settings - 8086 CPU, XT architecture, and CGA graphics. I also tried ET4000, to no avail. I got all the BIOS files from the website linked from your Bitbucket wiki (except for the CGA BIOS), and the same configuration works fine in the Windows version - it boots into BIOS and reads floppy disks correctly. I'll be thankful if you can help me out.