A leak has sparked speculation that Nintendo has created an official Game Boy Advance emulator for Nintendo Switch Online. Nintendo Switch Online, or NSO, is a subscription service for the Switch console that includes features such as online multiplayer, cloud saving, and a library of games for past consoles like the Super Nintendo Entertainment System. Recently Nintendo released an "Expansion Pack" for NSO, which includes games from the Nintendo 64 and Sega Genesis.
Emulators are programs that imitate older devices on a computer or other chosen device. Once installed properly, these programs can emulate older versions of Windows, Macs, or gaming consoles such as the Nintendo 64 or PlayStation. They're typically used to run programs that wouldn't be able to work on modern-day devices, or if the user does not have the console the program would run on. These emulators are commonly used for gaming, both for the sake of playing vintage video games and preserving these titles so they aren't lost to time. Fortunately, through the use of NSO, Nintendo has already taken steps to preserve its own library of vintage titles and bring them onto the Switch.
Files and screenshots leaked onto 4chan, then shared on Twitter by user FivekNIghts, seem to suggest that Nintendo Switch Online may be getting Game Boy Advance games sometime in the near future. The screenshots seen include titles such as Pokemon Pinball: Ruby & Sapphire, Super Robot Taisen, Golden Sun, Mario Kart, and Mario Bros. The screenshots also display assets, or effects and features in the games themselves, such as color palettes, anti-aliasing, and a semi-transparent lens flare. The screenshots show suspend points, which are a feature already seen on NSO for its other consoles such as the Nintendo 64 and SNES.
The "authenticity" of this leak is presented by several links from Anonfiles, which is a website where a person can anonymously upload files with their IP addresses masked. These links supposedly contain a 7z archive and an officially developed GBA emulator straight from Nintendo. In several spots of the first screenshot, we do see "'Sloop' GBA emulator...(c) Nintendo". This would indicate that Nintendo does indeed have an official GBA emulator, called "Sloop".
It is important to remember that this is all speculation, and the "facts" and "proof" presented may not be accurate. However, as Nintendo Switch Online already has an impressive library of officially emulated games, it is not outlandish to think that they could expand on it even further. Whether there is any truth to this leak remains to be seen, but it's clear that there is still an active community of gamers who would like to see GBA titles added to NSO.
Source: FivekNIghts/Twitter