Does filing a flight plan with Garmin Pilot activate ACAS and SE-SAR for my inReach?
SE-SAR and ACAS are only available for flight plans that are either filed directly through 1800wxbrief.com or through an app that's linked to your Leidos account (1800wxbrief.com &gt; Account &gt; Service Provider Authorization).
Garmin Pilot isn't on the list of known service providers, so FSS won't be able to match your flight plan with your online profile... meaning these services won't be activated.
Some apps (like Foreflight) have their own built-in ACAS feed, separate from 1800wxbreif.com's SMS-based interface. If your app has that, it would receive ACAS messages directly via push message. Unfortunately, Garmin Pilot currently doesn't have this feature.
See also this related question:
Will Lockheed Martin Flight Services send me ACAS, EasyActivate™, and other text messages if I file my flight plan through ForeFlight Mobile?