So, I was using Neko Tracer to look into Last Armageddon.
I believe I've found the line of code where it loads a character of text.
I think there's some space free in the disk image. I typed some dummy text, loaded the game, and checked RAM. It's there. While I think this game uses the BIOS font, I suppose it shouldn't be too difficult (once I read up on x86 some more) to load a custom 8x16 font into RAM. (and also rigging it up to use a single-byte encoding instead of 2-byte-only Shift-JIS).
The docs with Neko Tracer indicate VRAM should be directly readable/writable. But would I still need to do some kinda vblank wait?
Since it appears PC98 uses 3 1bpp bitmap planes, I'd probably still have to do a VWF building "tiles" like I have to for SNES VWFs. But no tilemaps! (though I suppose an 8x16 font should suffice)