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.