GBARunner2 (2020/04/12) is released. GBARunner2 ia a GBA hypervisor for DS. By default GBARunner2 will look for a "GBA" folder in the root oft the SD card, and open it. Otherwise, it will open the root of SD card. Put roms and a gba bios as "bios.bin" in the "GBA" folder or the root of your sd card. Make sure the roms are sram patched if needed. Hidden or system files and folder won't be shown, so "bios.bin" file can be hidden.

GBARunner2 changelog:
This makes the average number of gba cycles per frame equal to a real gba,
but with the ds base clock. This fixes problems with games that use timer
sync for audio. Sample rates are also no longer fractions

Download: GBARunner2 (2020/04/12)
Source:Here