The problem is that they're not really made for this task, both in hardware and available software. They typically specialize in routing and switching, but have insufficient internal hardware (memory especially) to run a full-blown OS.
So whatever you install on these devices, will probably not give you all the features that you would like to have. (For example, a full linux command line with all the typical programs installed.) Also, it doesn't allow you to use HDMI to connect to a monitor, so there's that. But basic linux things can be done on it, if you figure out how to get to the command line. But it's very limited.