The (L)GPL license only requires you to offer source code to the customers (the people that get a copy of the binaries).
The (L)GPLv2 requires offering physical copies of the source, so the required information is in a printed notice in the box (on the first tablet).
(L)GPLv3, which e. g. Qt is under, allows for only distributing the source digitally.
The full list of licenses for all pieces of software are on the device as well, and the SSH information is available as a part of the license page (explaining how the (L)GPLv3 requires companies to give access to the devices/anti-tivoization).
someone seems to have ported a terminal already https://github.com/dixonary/fingerterm-reMarkable