Recommending Garmin Explore over Komoot (I use both): Garmin works offline - you can plan routes while you are on hike and want to change your plans.
WorkOutDoors is
the only app at the moment you can use to preload offline vector maps to watch, but it has serious limitations compared to Garmin built-in maps (on Fenix, ...): you can only pre-load a small area (compared to whole continents on Garmin) and it cannot route to a point (Garmin routes in watch fine).
The outcome is that with Garmin you can be assured to always have a map (and hiking navigation) on your wrist, while as you need remember to plan ahead with Ultra.
Also stating the obvious: With Ultra you need to take a battery back with you for anything but an overnight hike. With Garmin Fenix 6X I take a battery and charging cord for anything more than 2 nights just to be sure.
Overall, Ultra is inferior to Fenix for hiking. If that is an acceptable compromise for being "smarter" almost everywhere else remains to be seen.
My thoughts
comparing Fenix and Ultra as a blog post here.