I have been using saves from my SD2SNES, which are in .srm format, all I needed to do was rename them 'cartridge.sram'.
I would recommend this method:
- Load the game you want to copy saves over to and save a game on the switch
- Use Checkpoint homebrew to do a full backup of all your saves
- Open up the Checkpoint folder, find the game you want to use your retroarch save for, and save over the 'cartridge.sram'
- Restore saves using Checkpoint
I would recommend this method:
- Load the game you want to copy saves over to and save a game on the switch
- Use Checkpoint homebrew to do a full backup of all your saves
- Open up the Checkpoint folder, find the game you want to use your retroarch save for, and save over the 'cartridge.sram'
- Restore saves using Checkpoint