In regards to my last post I think I may have just found the answer in the themes.md file and it looks like it's possible so that will make porting easier. (I should have looked more carefully).
@helpman said in [RETROPIE THEME - PORT POSIBILITY] Cardboard Mini NES + Nes mini and Famicom mini themes:
Hi! I just bought a nes case for my pi3, and I'll be here just waiting for that port too I just LOVE the nes theme @ruckage made... crossing fingers for recalbox port
Port is definitely coming, I've been reworking things in the retropie version to make porting to recalbox and then maintaining both in the future easier.