I know when you call from a cell phone it does this but since Inreach is GPS I was not sure...seems to be that for some emergencies I would not need GEOS, just local 911
If it was me, I would not depend on this.
First off, SMS to 911 does not work everywhere.
Secondly, tracking the originating location of a cell-phone initiated 911 call is still an iffy proposition. This means that routing the call to the proper 911 dispatch center is also iffy.
The real issue, though, is the manner in which SMS messages sent from an inReach device are routed and delivered. Cell towers are not involved. SMS gateways are used instead. To me, the chances of reaching the correct 911 dispatch center in this manner are minute. And that's assuming that the Garmin servers would even forward an SMS directed to 911.
You'd have to ask tech support for a definitive answer. But I doubt that it's going to work.
Do note that GEOS is an intermediary, not a response organization. If your local fire, EMS or police department is the proper responding agency, that's whom GEOS will contact.
As twolpert mentioned and according to the FCC, text-to-911 is not available everywhere, see https://www.fcc.gov/consumers/guides/what-you-need-know-about-text-911.
You may want to take a look at inReach Webinar - What Happens When You Trigger an SOS?. You'll see that when you trigger an SOS, you're put in contact with GEOS in a two way message conversation and you can let them know that you only need assistance from local law enforcement and they can respond accordingly.