In multi-planet systems it can get confusing as to what teleporter is linked up where. I propose making them colour coded at random. So for instance, the first pair you link up might have a red glow, the second a blue glow, the third green and so on. The colours would have to be randomised though - if 1 was always red, 2 was always blue etc, it could give away too much intel.
As an addition to @eukanuba 's suggestion, it'd be excellent if you could ctrl + click the teleporter and it Pinged the linked gate
If you hover your mouse over a portal and have the PiP on, the PiP should show you which portal it is connected to. When you move your mouse off of it, it should go back to what it was showing. Or maybe if your PiP is off, the PiP turns on temporarily while holding something like Shift over a portal.
This would be really nice to see added, maybe have it thrown in as a "polish" update along with the orbital team color travel line which would also be really nice to see. Good post OP
I really like this idea!! Ctrl click shows the other teleporter in pip or in the main window when pip is closed since you might not recognize it when the teleporter is shown on a small alert popup