Last time this happened, there were two effects: on one hand people making fun of not being able to upload their activities to Strava and on the other hand, and more seriously, people not being able to use their aviation navigation systems. Can someone comment if the Garmin aviation devices are affected?
Garmin glass cockpits don’t depend on Garmin services at all. Perhaps updating charts but that’s a monthly thing generally and it’s not done while airborne.
The “not FAA approved” isn’t a thing — there are devices that go in uncertified (experimental) aircraft, but those also don’t depend on live connections to Garmin services.
Likely they are, likely it "shouldn't" matter, as all their advertising says: "Not FAA approved [wink]"
...like, in an emergency it's cool to be able to click a button on your watch and see the closest airport, but you're supposed to have paper maps, a flight plan, a checklist, etc, etc.