It seems weird that the local district’s competitiveness would affect the national weight. The whole point of first-past-the-post voting is to pick one person for everyone. Under your proposed system, people who didn’t vote for the winner lose their influence on the national level. It would probably influence people to vote for the perceived winner instead of their choice.
It might work better under approval voting, where you can vote for as many candidates as you want, but still would encourage people to vote for whoever they think is going to win.
Good question, it’s an interesting idea!
I did miss that, thanks for pointing it out kindly.