I do rollerblading and rollerskiing, and would like to use the Varia for those activities. I've tried mounting on the back of the helmet, and it works, but only in a cycling activity on my Fenix 5. As it stands now, I have to use a cycling activity instead of cross country skiing while rollerskiing for the Varia to work. Why can't it just work with all activities when connected? Obviously it's not gonna be connected if I go out for an activity where I don't need a radar!
It would be good for running on a shared bike/walk path, too, mounted to the back of the shorts for example.
Using it when rollerskiing is even more useful than cycling, because 1) It takes more space on the road, especially if doing skate technique or inlineskating, 2) It will show cyclists approaching fast when on a bike path, and you can't hear those (road racers seldom have bells, even though they're mandatory here in Norway) and 3) It's harder to constantly look back when rollerskiing than cycling (my personal experience).