Using python generated web page as input for Pygame controls
This is not possible.
PyGame is intended for rendering graphics on the computer running the Python binary, while Flask is intended to generate HTML to be sent to a remote computer. The only way to interact with a remote user through a browser is through HTML and JavaScript.
Moreover, this there is no way to interface PyGame with HTML/JS because PyGame's method of accessing the local screen, keyboard and mouse is very different from HTML's method of interacting with the user. To give just one major obstacle, PyGame's fundamental mode of operation is to block the UI thread until an event (such as a mouse click) occurs, using the function pygame.event.wait(). In HTML, by contrast, this is not allowed, and you are expected instead to register handlers for events such as mouse clicks.
I am currently working on a project that would allow me to serve a web page to multiple local devices and use each client as controls for Pygame input. I am having trouble finding out if I can even pass data in-between the two (Pygame and flask) let alone having them run side by side using something like async. (Please note i am just getting started digging into python programming). I was thinking of two ways that this could happen if it is possible to have them communicate.. 
1) Use flask to pass the data to Pygame.
2) Use something like Brython to run python localy on the device via browser and connect them using sockets.
Is it possible or is this just a pipe dream?
Thanks,