The software you ran on a 25MHz machine was in all likelihood written in assembly, directly interfacing with the hardware of your machine, without even touching your windowing system (if you even had one, maybe you were running DOS). Modern operating systems frown on that sort of thing with extreme prejudice.
Wasn't SDL supposed to be that? What happened to that?
How is Vulkan more portable than a software renderer? And if you need hardware acceleration, OpenGL is more portable than Vulkan.
I would have thought SDL is probably a better target for this type of application. However, I'm happy to see developers use what they like and push the envelope how they like.
Just upgraded to Linux kernel 5.3 and beta mesa & vulkan so I can drop in my rx5700xt, which I still need to do.
The advantage that opengl has is a number of software implementations that can be used as a last ditch on unsupported systems. Efforts for software vulkan implementations are taking a long time to appear.