Body Battery appears/disappears on the same graph. Shall we create an IQ App or Widget ?

From the article Body Battery Frequently Asked Questions | Garmin Customer Support

How Is Body Battery Tracked If I Wear Multiple Watches?

If you alternate between devices throughout the day, the body battery data in Garmin Connect will only be from the watch set as your Preferred Activity Tracker. However, you will still be able to see body battery data on the watch widget/glance screen from the non-preferred tracker during the time it is worn.

NOTE: Body battery is not a feature that utilizes TrueUp so you may see a difference between the body battery stats from one watch to the other.

Body battery is a newer feature which is not a part of Fenix 5+'s feature set (it was added to Fenix 6 and later models). That's another reason why you wouldn't get Body battery from your Fenix, even if you set it as your preferred activity tracker.

Thanks for the info, I would like to invite garmin to activate TrueUp also for stress and let me see the body battery even when I wear Fenix 5x Plus the body battery is an algorithm calculated on stress.

NicK said:

I would like to invite garmin to activate TrueUp also for stress and let me see the body battery even when I wear Fenix 5x Plus the body battery is an algorithm calculated on stress.

As far as I know Fenix 5 does not support Body Battery, hence it won't happen even if Physio TrueUp is enhanced to sync Body Battery too.

I understand that there is no body battery function in the 5+ series but I have the 5x plus which is equipped with a pulse oximeter like the First Avenger. Also we have the stress graph and the BB is calculated on this graph, therefore, we can create an app.
I don't think Garmin will lose any customers if they add this metric to their stress graph.