It’s an legit 8-bit CPU implemented with TTL chips, what makes it a different beast than what they did back in the days is that its microcoding isn’t kneecapped. It would absolutely have been possible back in the days to build exactly such a thing, even from precisely those components. At least the TTL part, that is, I bet there’s wibbles around VGA etc. And because I already hear the detractors yes, 8-bit CPUs were microcoded: They decoded single external instructions into a stream of “load from memory, fetch from register so and so, switch on the ALU, put what’s in the ALU output somewhere”. They kept it as simple as possible and it wasn’t reprogrammable but that stuff there, that’s microcode.
Implementing CPUs in TTL chips also isn’t a new idea, that’s how early minicomputers were made (later on they got some specialised chips). And those things also used ROMs for their microcode. So you could say that this is a minicomputer capable of pretending to be different 8-bit microcomputers.
FPGAs are a completely different technology, those allow you to arrange logic in a (more or less) arbitrary topology. That is, looking at that board with all those TTL chips, it’d be the equivalent of being able to re-route all the board traces as you please.