Quick fix

Make sure usb2snes is already working with your setup. Then have windows open the .sfc or .smc file using romloader.exe. As long as everything is fine with usb2snes it'll copy the rom to the /romloader directory (creating if it doesn't exist) and then boot the rom.

You can find usb2snes for sd2snes firmware 1.9.0 here: https://github.com/RedGuyyyy/sd2snes/releases/tag/usb2snes_v9

Only a small bugfix behind the scenes. Now the app will identify itself with the websocket server so it can be seen more easily in logs for troubleshooting.