Need advice - where to start to show game in continue about foos HOT 1 OPEN

There shouldn't be any performance issue - I think the chip will handle the video preview without issue.
You'd have to do the following at least:
Change the preview size by adding this to your conifg.py file (adjusted to your resolution)
camera_preview = "-p 0,0,1920,1080"
That should show the preview fullscreen.

The problem is that the screen layout for scores is not really confgurable, and has two modes: normal and overlay_mode (small counters top right). You can modify the counter size and position in normal mode here:
https://github.com/swehner/foos/blob/master/foos/ui/ui.py#L324-L333

There are some other components that would have to be changed, but that shuld be a start...

from foos.