If I select my SM64DS nds file it goes to another directory page and says “no content” instead of suggesting a core or booting the pre-selected MelonDS core.
I already put the required bios files into the correct directory.
The core may be busted apparently,last time I ever attempted to use it,the core would crash because I didn’t have bios set up previously.
Using RetroArch 1.7.7 aarch64/armv8 downloaded from here in the nightlies.
It’s probably better not to fool with it until the big update hits to bring it more up-to-date. It’s being tested for rollout right now and should be coming relatively soon.
Okay,thanks for the info. 
Hope it can get up and running soon maybe so I can check out performance compared to the DeSmuME standard core.
Also,I found that it does load the list of cores once I added DeSmuME and when selecting MelonDS it goes to that same message so the core is indeed just outright failing to load altogether.
Someone just told me a couple of hours ago that the core has already been updated on some platforms, at least. Not sure if Android is among them. I’ll try to do some testing soon.