The CEL on 3DO is not working the same as the blitter in the Amiga. Although it still "blits" bitmap scanlines horizontally and then moves up vertically in any direction and scale, like it uses two vectors and one more to fit a bitmap to any quad area on the screen, so it's doing texture mapping in a sense, drawing textured polygon quads. But if you manipulate the vectors, you can do weird things like curved polygons, very thin one pixel polygons to make line rendering, etc. But at the end of the day, if you write a 3D engine on CPU and you transform/project points to the screen, now you can create the 3 vectors from the 4 quad points and have it fill the quad area with interpolated texture without you having to do that part in software rendering. Makes things possible on 3DO that you would need a 486 or maybe Pentium to do at the same speed. And it's very simple if you understand how it works.
I've seen the guy's work on his channel, he also posted on our 3DO discord once.
p.s. Something else I thought. I said I did something on 1999, then on 2006 I had a first 3d object engine (with gouraud, texture map, fake envmap like in the demoscene) and it seemed like a miracle to me. But at the time I was a bit slow, jumping from project to project, also doing 2d demoscene effects, also doing 8bit assembly on Amstrad CPC, studying for univesity, trying to find a job, etc.. so progress was slower but it was ok with me. But now I realize, if you focus enough you can do a simple 3d engine like in few months. If you see Tsoding's video "One formula that demystifes 3D graphics" you see that a toy 3D engine that does all the mystical things is much simpler than one would think. Of course for extra things (visibility culling, polygons, etc) there is a bigger road head which I took with Bizarro Untergrund. But those are gradually solved if one focuses on the same project and not leave it dormant and jump to other things. All my previous examples were a 3d object rotating in the center of the screen but if you zoom too close it would get nearZ and crash. But enough for a simple demoscene demo :)