Re-thinking a bit: The trouble with pots is they won't be there when you don't bring your full gear. Why not just put a small PSK into a wide mouth stainless steel water bottle? The wide version of the Klean Kanteen comes to mind, find the appropriate size here:
Klean Kanteen dimensions

For boiling you need to add some suspension method, a wire loop should do the trick. The budget version is to cut off the outer shell of an old thermos, just below the threads.

The perfect PSK container would for me be a square stainless steel "lunch box" shape that is thin enough to slip into a pocket. Much better volume/size ratio than a cylinder.

I am also testing the less reliable method of folding a flat cup that fits into your PSK. With my current setup, I can make one about 4 by 5 inches that holds about 14 cups (a bit more than 4 dl). You need the thick aluminium baking pans for this to work - and you make the cup at home, not in the field. Far from perfect, but leaps ahead of the aluminium foil trick that is included in some PSK's.