You don't need to do anything special for this except add orienteering as an activity type for those of us who use forerunners for orienteering training and events so it's easier to see my orienteering events. Off road or xc running would also be handy for those of us who run but not on roads and trails but I'm less bothered about this. Alternatively you could have a box where we put our own activity type.
Yes please! Garmin devices are used by lots of orienteers. Having Orienteering as an activity type would make our enjoyment of Garmin Connect so much better!