The killer app for the on a Linux network is Term48 —a terminal emulator in the BlackBerry World (RIP) archives. You can sideload it.
While running Linux on the BlackBerry Q20 is possible, there are several challenges to consider. The Q20's hardware is quite specific, and not all Linux distributions are compatible with its Qualcomm Snapdragon S4 Pro processor and 2GB of RAM. blackberry q20 linux