This is a system information tool, but it contains a read-only "File Viewer" tab. You can scroll through proc/ (process lists) and dev/ (device drivers). You cannot edit anything, but it is technically a file explorer for the Linux kernel underneath the 3DS OS.
: Its functionality is extended through plugins, including specific ones for 3DS cartridge dumps and common compression formats. Official Source : The project is hosted on the Gericom/EveryFileExplorer GitHub repository Alternative File Explorers for 3DS every file explorer 3ds