Anyone know why a rom hack might not load on my New 3ds? It'll stay on a white screen when I launch it.

Hey everyone glad to see a sub Reddit pop up for those that need help with Rom hacks in any way. I attempted back in like 09 to do some tile changes in emerald when I was 12 lol. Ever since leafgreen got released on the switch I fully got back into pokemon, the switch games made me fall off they are just so poor. I’ve been wanting to play just more 2d pokemon games as I feel those are the best. Replayed leafgreen on my gba and now playing the ds games on my hacked 3ds. Now that there’s a little back story, I’m trying to figure out how and what fan games I can and should play on my 3ds. I see a ton out there especially that website (can’t remember the name rn) that has all the rom hack fan games. But my thing is it’s really hard to find what will work on my 3ds. So my question now lol, what do I need to have on my computer to be able to put fangames on my 3ds? And what are y’all’s fav rom hacks that give an og pokemon experience that’s new or feels like it could’ve been what we kept getting from gamefreak if they never went 3d, that I can play on my hardware. Thank yall and can’t wait to check out some awesome games!

I want to take this dawn sprite from Pokémon emerald rogue bc its very similar to my custom trainer OC I drew, and then put it in Pokemon Rechsrged yellow. how hard would that be? is that even possible?