Lots of people talking about what this new Ultra "can't do". I've been using it for Ironman training since launch day... that's a reasonable high-end fitness use case and honestly, it works great. You have to lean into the 3rd party ecosystem, which I was hesitant about, but no longer.
Download structured workouts from TP: iSmoothRun
Swimming: works better than my Fenix 7s for swim stroke detection + drills and kicks - nothing needed
Biking: Any real cyclist is using a bike computer anyway, me too. That said I do also use WorkoutDoors which connects to my BLE PM and other sensors
Body Battery / Readiness: Athlytic or Health app - pending how much you value gamification vs raw data
All my workouts are in TP anyway, and that's where my coach or I would do real analysis.