This game has hidden development-related text.
Pac-Man 99 sees Arika milking the Battle Royale format once again for the Switch, this time utilizing some elements from the Pac-Man Championship Edition series and throwing in paid DLC (something that Tetris 99 and Super Mario Bros. 35, also by Arika, had avoided).
Speaking of SMB35, this is basically the replacement for that game, which had been shut down a week earlier.
Windows Build Assets
Every single *_rom.*.dat and *_rom_file.*.dat in the Dat folder has similar files ending with .x64, providing identical assets but cooked for Windows.
Empty Theme File
Also present in the Dat folder is dbg_theme. While the name suggests it was used for debugging purposes, it's completely empty.
Internal Project Name
The build path of the game suggests the game was internally called yosso.