You're likely thinking of Yuzu which was a switch emulator. Nintendo probably targeted them because they were about to launch the switch 2 and wanted to send a message.

They planned to release on steam but Nintendo prevented it. The project however still exist standalone.

The switch emulators Yuzu or Ryujinx perhaps?

I think that was Citra emulator. Protect Dolphin at all costs!

Nintendo (among other creative corporations) do not seem to realise that invite to play creates an attachment to the product that is deeper than a license agreement, which is our shared cultural filament.