That is true, Pixel cameras lack controllability to ensure the same configuration is used between shots, can’t do beamshot comparisons. Using third-party camera apps may enhance controllability, but loses the low light capability of Pixel series.
if they provide full manual control, then you’ll do just fine in low light by setting long exposure time, and opening apperniture wide. you can also increase iso. thou some cams i used would make pic more grainy with higher iso in low light, in that case you want lower iso.
that does the same thing as low light auto adjustments, the fact that pixel can adjust EV that much is great, assuming manual mode app can also go that far on adjustments, so if the app can access full range of exposure adjustments of the pixel, you do not need any other camera.
i wonder if wired\wireless headset can work as remote shutter button