I was just looking into that after hanging on to Movescount for as long as I could! Luckily, we can get a .gpx file from Attackpoint quite easily.
Exporting a .gpx file from the Suunto app is supposedly possible but a bit awkward. From the documentation:https://www.suunto.com/en-gb/Support/faq-articles/...
Do you want to use the route or the recorded data you have in the Suunto app with another service?
You can export both the .gpx file (1) and the .fit file (2) of your training from the Suunto app.
1) Open your saved routes gallery and tap the Share button. Send the .gpx file to a friend, AirDrop it, save it to your Files, or your Google Drive. Additionally, you can go to your exercise, tap the "More" (three dots), and save the route to the gallery.
I've tried this. Attackpoint doesn't recognize the .gpx file as a .gpx. Because I can get my Suunto app data into AP and generate a .gpx file from there, I haven't pursued it farther.
I have an Ambit3, and Suunto really doesn't care about older watches. In this case, it sounds like even people with newer watches are scratching their heads. If you look in Suunto forums, there are many unhappy people. Suunto was selling new Ambit3 watches on their website until very recently.