I'm still playing around with Carb Manager, so far I've only stumped the recipe calculator in it on an ingredient a few times, and was able to find a workaround for those0, but it doesn't have apple varieties, just generic 'apples', with or without the skin/core. I'm getting a bit faster at it, I was playing around with keto-friendlier recipes for apple pie filling and pie dough last night, I think I can get a slice (1/8 of a pie) down quite a bit:
Crust (original) 23.5 carbs 23 net carbs, 248 calories
Crust (keto) 15.4 carbs, 5.4 net carbs, 225 calories
Filling (original): 40 carbs, 37.3 net carbs, 154 calories
Filling (keto): 39.9 carbs, 12.2 net carbs, 56 calories
(Most of the carbs are from the allulose, 22.7 grams)
So that means a slice goes from 63.5 carbs, 60.3 net carbs, 402 calories to
55.3 carbs, 17.6 net carbs, 281 calories.
Whether it will still taste like apple pie remains to be seen.
Update: Yup, looks and tastes like an apple pie.