I discussed this same idea already with several ppl @arkinox @bitpopart (nostride.cc) and @fiatjaf (about if it would make sense to fit the GPX spec into a NIP / event kind)

I use Strava a lot (for my activities) and also Komoot (for building cycling and gravel routes).
So if anyone is going to build this, I would like to be involved 😉  

 Yes we will do the cycling🚴‍♂️🤙 and I hope also some day to add my #photography @traveltelly with GPS in it to a Nostr app. Have still so much content from around the world📸