Two words about the first feature: plain and simple!
It's easy and work well. I'll resume my recommandations to refine the function:
1 - When I enter .2155 km or 0,215 km, the watch always rounds the lap to 0,21 km. So more precision is needed as we want the same precision indoor as we can have outdoor

. Ideally 4 decimals

. If not possible, 3 decimals should work too.
2 - Change the feature name to avoid confusion. Personnally I would choose:
Activity setting > Lap setting > indoor distance or indoor track distance or indoor preset distance. Because indoor stands for GPS off.
3 - Simple Lane distance calculator utility incorporated into Training Gym Pro.
4 - If I choose
AutoGPSOffLap, then do my indoor training and turn off my watch. When I turn it on again to make another indoor training the lap setting is back to GPS OFF. Could it stays to
AutoGPSOffLap so I have direct access to it when I return to indoor training mode?
5 - Maybe the GPS fix window and the indoor window can be a little confusing. But I read somewhere that that this cannot be change (acces directly to indoor mode). Is that it? At least can we change the order of appearance?
Next step is indoor distance and speed lap. It will then change from two to three words: plain, simple and brillant!