I would argue that 1024 mb RAM could indeed handle it. There are many, many Android phones around that quantity and they still seem to run OpenMW fairly fine (except for performance, around 20 fps)
Same as any other mod, except in OpenMW.cfg you add this: content=insertmodname.esp or .esm
Edit: Question, would anyone be remotely interested of multiplayer Morrowind on the switch?
It has to be like this:
/switch/openmw/data/mugman16/saves/[insert_character_name]
And please make sure the save files are from openmw, not from the original Morrowind.