I figured this was true back when the Nintendo Gigaleak came out, but shortly after that a series of romhacks were released that included assets from the Gigaleak. One I can think of off the top of my head is the Pokemon Crystal Spaceworld 1997 Romhack that would’ve only been possible with the Gigaleak.

So theoretically, you’d be correct but I think it ultimately depends on how passionate the modding community for this game is.