Is ATAK even useful to civilians? Is it trustworthy?

Yes and yes, we've used it for civilian Search & Rescue in tandem with CalTopo.

I use it for hiking, its great.

How do you use it for that?

It is an offline moving map with very fancy marker etc support. Seems a good choice for a hiking app?

Can design then export routes from any geospatial tool like CalTopo, AllTrails, or even WinTAK directly to your ATAK device. Then in ATAK you can use it basically as something like AllTrails on steroids, including offline map caching, route guidance, markers, tracking etc... even geotagged photos. This can be synced across multiple devices among friends using a TAK server. It can also be used for off grid communications and tracking between hikers via something like Meshtastic, which I use fairly regularly with my partner out camping well outside of cellular coverage.

ATAK is not necessarily the most intuitive UI, but it's crazy powerful for doing basically anything outdoors.

If anyone wants to help make MANETs better with TAK… check out opportunities on ditto.com where the team is building crdts and using them to help enable SAR. Say Turner sent you in your application if it looks interesting. Particularly the FDE role.