Could Canada build a complete modern jet fighter with missiles and
radar? Assume they have lots of money (10-20 billion dollars) and
seven or so years.

Canada is actually well positioned to build the airframe. Bombardier
has very significant experience building subsonic jets and presumably
could handle supersonic jets with time and money. The science behind
this is VERY well known. Heck even Burt Rutan can do this, surely the
nation of Canada can.

Pratt Canada builds lots of gas turbines. They specialize in smaller
jets but again given time and money could likely scale up.

Radar is a problem. Web searches make me believe that Canada only
builds radars for atmospheric research and air traffic control and one
military radar, which is used by maritime aircraft for periscope
searching.

Missiles are another problem. Web searches suggest that Canada builds
no missiles and more importantly no seaker heads. They might have to
start from scratch on this.

So, can Canada build a modern jet?