Yes the poco has the same 12MP sensor as the Pixel 3 and 3XL
Gcam makes it even better
Its not just that simple:
Note 7 Has 48 MP, f/1.8, 1/2", 0.8µm (Chip only allow for 12 MP so no seperation of 4 grouping)
Note 7 Pro has 48 MP, f/1.8 at 0.8µm (Can run both 48 and 12 MP by grouping 4 as 1)
Pocophone has 12MP f1.9 at 1.4µm
Pixel 3 has 12.2 MP, f/1.8 at 1.4µm
Both the Notes and the Pixel has better Optics (f/1.8) than Poco's thats only (f/1.9)
Also the Photon pickup size of the Notes (1.6µm) are bigger than Poco and Pixel (1.4µm) when you run them as 12 MP.
In conclusion Hardware wise Note is better than both Poco and Pixel As it has bigger pickup and same quality optics as Pixel.
Pixel's Optics is better than Poco so it will win hands down
What we dont account for is Pixel's AI software (Not Gcam only) that is way better than both Note and Poco. Xiaomi have way too much noise in translating/converting photon's to image in the hardware.
So I would say looking on paper quality would be:
Pixel > Note 7 Pro > Poco.