Various leaks have demonstrated that Nintendo is working on expanding its Switch Online service. Soon, Nintendo Switch Online will be capable of emulating Game Boy, Game Boy Color and Game Boy Advance classic titles, adding to the N64 and SEGA Mega Drive games that the service can already emulate.
https://www.notebookcheck.net/Nintendo-Switch-Evidence-of-Game-Boy-Game-Boy-Color-and-Game-Boy-Advance-emulation-leaks-for-Nintendo-Switch-Online-service.614667.0.html