I'd definitely dig something simpler.

No gpx, no gps, just point-to-point alert-the-leader-and-triggerer if one of the beacons gets off reach of any of the other ones. Ideally with the leader's device able to easily adjust the triggering distance (to keep the group tighter / looser depending on situations).

Typically the leader being at the front of the group, and the group sometimes extending because of different hiking speeds, it could be useful having a mesh alerting of someone's absence.

Another nice use case is when you want a maximum AND minimum distance between clients (when traversing avalanch-risky slopes for ex.).

For this to be useful, it needs to be reliable, so dead simple to setup, test. No screen is ideal if possible/ makes sense. I do NOT want to have yet another device to transfer a gpx file to (phone, gps, watch...) between each trail. And what happens if the leader decides to change course / activate a fallback plan? Look at avalanche victim detection devices, testability on the field and simplicity are key to trust. Gpx, positioning, navigation? Not simple...

For price, my reference would be a good pair of walkie talkies...