Is it possible yet to (without hoops) have an action workflow that runs on pull requests to <default_branch> without having to name that branch explicitly so th

Is it possible yet to (without hoops) have an action workflow that runs on pull requests to <default_branch> without having to name that branch explicitly so that you can have a write-once-run-everywhere-forever process across repos that might change their default branch name? Last I saw there was a template parameter, but those get populated at creation not at runtime.