For me, I hit Command+Shift+P in VS Code, choose Open pull request, then hit Enter. As easy as it gets.

https://marketplace.visualstudio.com/items?itemName=GitHub.v...

Git aliases to the rescue:

    pr !open "$(git remote -v | grep origin | grep push | cut -f 2 | cut -d " " -f 1 | sed -e "s|git@\(.*\):\(.*\).git|https://\1/\2|")/pull/new/$(git rev-parse --abbrev-ref HEAD)"