I've got both, a DEFI boost gauge and a P3 gauges vent gauge installed on my 1.2 TSI.
The DEFI has its own sensor that you install in the engine bay and use a boost tap to plumb it. If you have a Forge Motorsports BOV, you could just T off its hose.
The P3 vent gauge comes in 2 models, a boost gauge and an OBD must gauge. If you buy the boost gauge, you get a similar boost sensor that you plumb like the definition. If you go for the OBD multi gauge, you can use both a sensor or without it. The multi gauge shows you the boost that the ECU sees. It also is capable of Coolant Temp, Intake Air Temp, Exhaust Gas Temp, Throttle position, Vehicle Speed, RPM, Shift-light, Battery voltage, 0-60 timer and AFR.
Installing the vent gauge on the Polo is a complex task. The vents on our car is removable as a whole unit but the fins on the front can't be removed individually like the golf.

- FOR-VW-2014-POLO-Polo-chroming-dashboard-air-vents-Outlet-Piano-paint-cover-trim.jpg (26.47 KiB) Viewed 3192 times
SO,a bit of cutting, grinding using a dermal and you can install the MK6 gauge on the polo. Bear in mind that the display also has to be modifies a bit (cutting, trimming) since the MK6 vent is longer. But overall, totally worth it.
Attaching pic of my setup.
https://youtu.be/BN7equbVPGg
P.S. If you have a piggyback chip tuner, you can reference your actual boost using the separate boost sensor and see the boost that the ECU sees using the OBD.