Mmmm. I dunno. You’re talking about location availability off the hardware?
Last month, I had to call 911 when some random druggie lit what I thought was a building on fire across the street from my car (it turned out to just be a bonfire in the parking lot; figured that out while running over). I didn’t know the cross-street for my location, and asked the dispatcher if she could just send the fire department to the location she got from my cell phone via E911. She had no idea what I was talking about, needed me to manually provide location.
So I’m not totally sure, at least in the US, what the compliance requirements are for availability of location information.
If you’re talking about 911 usability without logging into a phone from a lock screen, I don’t think that that’d create any issues – that’s all software, can do whatever if you’re doing the OS.