I looked at the Garmin spec sheets before buying my Apple Watch and didn't find any of their computer/watch combos listing ISO 6425. Instead they list a depth (usually 100M) and attest "Tested to engineering standard EN13319 for dive compliance", see https://www.garmin.com/en-US/legal/waterrating-definitions/
they seem like mostly a fashion / status symbol kind of thing
Yeah, this is my understanding from talking to diver friends. As a guy who likes watches yes, they're crazy popular in the watch community.They've become kind of a genre unto themselves. Citizen, Seiko, and others make affordable ISO 6425 models. I own a few, didn't pay more than $150 for any of them.
Though, I dunno about the "status symbol" aspect. For $30 you can get a diver-style watch that looks like an actual ISO 6425 watch unless you know specifically what you're looking for. So I don't think anybody would be impressed by them. But they are fun to own and rather handsome, if you like that kind of thing.
I stand corrected, but the same article also states:
“Water Resistant 100 m […] NOT suitable for diving.”
“Water Resistant 200 m [.] Suitable for skin diving only. NOT suitable for scuba diving.”
And, IIUC, WR100 is exactly what the Apple Watch Ultra has.
https://en.wikipedia.org/wiki/Water_Resistant_mark
ISO 6425 is much more stringent and specifies that every single unit is pressure tested to 125% of rated capability, ie a 200M ISO 6425 watch has been individually tested at 250M for a period of time.