MAME-NX Release 2.1 is released. MAME 0.72 for the Nintendo Switch. Roms go into /roms subfolder. You need MAME 0.72 roms for this to work. Source code included.

Quick Control Guide::
In Menu
Left/Right Trigger - scroll rom list
Dpad Up/Down - go up/down a single selection
A - Start Rom

In Game:
Dpad/Analog - Movement
Minus - Coin Up
Plus - Start
Right Analog Down - Mame Options Menu

Plus + Minus - Quit back to Rom Launcher

MAME-NX Release 2.1 Changelog:
ROT90 fix

Download: MAME-NX Release 2.1
Source: Here