does fenix 5 have an average heart rate per lap?

or just over-all aHR?

and is there any way to customize the black "lap results" data screen with aHR/lap?

edit: found the aHR/lap. still wondering about the "lap results" data screen. thanks

In the settings for the activity go down to the Auto Lap section - Lap Alert and you can modify the two display parameters, including adding lap Hr (which from what I can tell is the average over the lap).
I don’t think this can be displayed in GCM after the activity is uploaded (the Lap page only shows max HR per lap) but does show in the non mobile application.