We have seen these before :
https://gbatemp.net/threads/a-weird-switch-demo-unit.560877/page-8
This is the atmosphere version form you need
https://github.com/ZachyCatGames/Atmosphere/releases
Kiosk switches have a burned fuse that forces them into demo mode, this version of atmosphere patches out that check.
Then you should be able to use if with a CFW.
Turning it into a Switch that can boot OFW and go online is not possible afaik.
The cartridges are probably the games that are installed on the Kiosk.
Usually such units are labelled 'not for sale' to prevent vendors selling of such items for an extra buck.
I presume they can be installed and played afterwards without the need for having the cartridge inserted.
That would be an interesting thing to check.
You can dump those cartridges with another Switch running CFW or do it after you got Atmosphere up and running.
If there are any tools besides games then consider sharing it with the developer community anonymously.