No, the only known copy of Star Wars: Battlefront 3 hasn't been found

techradar.com:

A Redditor claims to have sourced the only physical copy of Free Radical’s canceled Star Wars Battlefront 3 video game, raising the excitement of Star Wars fans online. But don’t get your hopes up, as it’s probably not what it seems.

An image of what looks like a PSP playtest disc labeled Star Wars Battlefront 3 was shared on Reddit by user MissFeepit, alongside several photos of the game running on PlayStation’s handheld console.

The Redditor says they came into possession of the disc through a family friend, who playtested LucasArts games around the time Battlefront 3 was in development. They had been given the PSP disc to play but never returned it.

The images show what appears to be a loading screen, main menu, and single-player game mode selection screen, which shows options for “Instant Action”, “Campaign”, and “Galactic Conquest”. All three game modes were included in the first two Battlefront games, although the Redditor also mentions that their family friend remembers playing Capture the Flag, battles against the AI, and Conquest.

But as one Redditor pointed out, the photos more likely show an early build of Star Wars Battlefront: Elite Squadron, a PSP spin-off released in 2009. Its game mode selection screen certainly looks remarkably similar to those images shared on Reddit, with two Clone Troopers staring at each other from the sides of the screen. Although the disc is labeled Star Wars Battlefront 3, this may have simply been the game’s internal title before it was released.

The Redditor originally said they were interested in selling the disc and were curious to know what it could fetch. Others, however, suggested they try to copy its content and export it to a ROM file – which could be run through modern PSP