Integration with Apple HealthKit would allow btwb to pull weight, sleep and other data automatically without needing to manually log in multiple locations.
Integration with Strava (and/or Garmin) to import running, cycling and swimming workouts directly into btwb to avoid needing to manually input workouts.
Honestly, for a paid subscription fitness app, I expected these features to be included already.
I'll also +1 this. It's pretty nuts that this hasn't been rolled out given how many years health integration has been on the table now. IMO, Illustrates some rather...unfortunate...aspects of this team's app development focus (also given the total lack of communication from developers around this feature and the regular bumps that occur on this thread...).