Hi Erwu117 ,
It would be possible, but it would be likely very slow, as you would want to run pose estimation + object detection + crowd counting all at once. Just runs at about 1FPS, adding the two other NNs would then decrease FPS further.
So I would suggest keeping an eye on the OAK Series 3, which should achieve about 5x AI performance, which would allow you to run all these features at decent FPS.
For streaming to webserver, see options here.