Much of what can be done via pavucontrol can also be done via the command line with pactl and/or pacmd
If calls on Mobian has the same implementation as calls on PureOS and you use a DAC/ADC, you might run into the same issues I did with calls getting funky with the input volume control. I have solved the issue by auto configuring USB audio devices when they get attached, I detail the solution in this thread (Calls with USB headsets and other audio devices) which may be useful to you.