I do not want a government inspector or scuba police checking my equipment against a government mandated list. This is a buddy team non-tech forum and this is not the specific solo forum therefore this is really a no deco, no solo, no overhead, no penetration discussion forum. Failure or loss of mask is a minor inconvenience in open water buddy team diving and surfacing direct or even delayed and including a safety stop is not a big deal for a truly advanced skill level diver, or should not be. Now, if shore diving, need to traverse a boat lane, kelp bed or some other impediment to a safe conclusion of the dive, please by all means carry what is needed to accomplish that per experience.
I have never lost a mask in 56 years of diving that I can recall but I have had skirts split, frames leak or pop, buckles give up buckling and it has never been a problem to conclude the dive. My buddy can assist the safety stop though my experience is that I can do safety stops and navigation adequate for the open water environment without a mask. No reason that diving without a mask cannot be something a diver practices now and then just like an air share drill. I know of divers to tether their masks for surf and kelp shore dives.
If I am solo, planning a shore dive involving a long swim or there is deco or penetration potential then of course I would equip to handle that situation, which might include a spare mask. Otherwise, no, the less I carry, the more minimal and robust my kit, the better for me. Buy quality gear, inspect and maintain your gear.