Ok will fix it. For menu it can be done but game controller handlers is out of my control
Wonderful, I'm sure expansion port support in menus will be great news to a lot of people! Thanks KRIKzz!

FYI, some other more minor issues I encountered:
1. Like with the OG N8, it can happen sometimes that consoles modded with NESRGB there is random video noise (like random pixels going on/off) across the screen, requiring a power cycle until it doesn't happen. This was reported before for N8, and some people were able to fix it by removing a component from the console motherboard, but didn't work for everyone.
2. For the first three attempts to use the N8 Pro there was a "No SD card" error message, after re-inserting the cart and SD card a few times, it finally worked and detected the SD card.
3. FDS sound is much better than before, but still a little off compared to real RAM adaptor. Not sure how to describe it, the sound feels smaller, and a bit more metallic. Maybe someone like James-F can look into it to find better tweaking. But it's already a good sound, so nice work so far!
Expansion cart audio is fantastic, I really like the presets for multiple consoles. I can finally stop relying on original carts for those, and that alone makes the PRO totally worth it

I also tested big ROMs like Legend of Link and they load fine!