Being clean shaven is a pretty much universally accepted safety requirement for PPE and SCBAs that require a seal. When we asked Navies and fire departments in countries with large Sihk populations what they do, they simply tell people to shave. Most countries also don't accept 'Viking' as a religion for an exception either, so no idea wtf we are doing (particularly as there are no religious exemptions for fire fighting SCBA in CAF policy).
Not sure if I shared this previously, but there was this recent story in CBC about this Sikh gentleman who is a volunteer FF is PEI that explains it better than I can, but generally religions allow for all kinds of exceptions for things like safety. And given that it's more than just a bit of facial hair to him, I think making the sacrifice to help people is pretty commendable.
https://www.cbc.ca/news/canada/prince-edward-island/pei-stratford-newcomer-firefighter-1.6426225