Garmin have an import API (I’m just setting it up with cycle.travel). I’ve suggested an “open this URL to get a polyline” intent to the Osmand devs and they’ve built it but I’m not convinced it’s live yet.
Thanks for the tip about Osmand, I'll check that out. If you're referring to the Garmin Connect Courses API (https://www.garmin.com/en-GB/blog/garmin-announces-garmin-co...), that's exactly what I've just got access to and plan to integrate with fairly soon...
