@SciresM has leaked on purpose via the Discord Reswitched channel, the script used on v1.0.0 to v3.0.0 PegaSwitch-enabled consoles to dump game cartridges, now you too can be baddie closet 'pirate' just like 'BigBlueBox', which is now more useful since they just leaked some 'master_keys' and 'HACToolGUI' is out.
Nintendo Content Archive (.NCA) is a file format similar to .CIA files on the 3DS. With the release of the dump_nca file by SciresM, you can now rip your own NCA files from retail Switch game cards. In layman's terms, if there was a backup loader available publicly, this would be what you needed to dump your own games to run on it.
For now, this doesn't mean much to the end-user, as any currently released Switch backups are not playable on any Switch, but that will all change soon with the upcoming Team-Xecuter Switch mod, and releases of 'Custom Firmware' by various groups with patches.