What actual testing has been done?
Nothing published.
however Air Canada did a thorough study in 2018. Seems there is no problem.
Will people be able to fly according to their religious beliefs?
No official answer.
Will military personnel be allowed to fly in Air Tanker if their civvy pilots have beards ( the exact plane military pilots can't fly with a beard?) and therefore are they at risk if so?!
No answer.
Just hopeless.