Apps All in one?

[Hicks.]

Yes. Especially since they both use First Beat algorithms.

Can you import Apple Watch data into Garmin Connect?

I always wondered if they both used First Beat because they tally so closely (I actually run using both the AW 4 and a Garmin Fenix 5). Where did you find that information?

 

[xDKP]

Hopefully, someone else can answer your question, I'm not a runner, so I have no idea about a marathon. Might try to search, seems that there's been discussions on the capability of the watch's battery for that.

Yeah I know - have run several marathons with it without issues but seems worse now