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.