As I discussed in the body of the post, don't skip the xanthan gum. It is what makes this recipe work at all. Be precise measuring it, it's really powerful and is easy to over-do.
Remember the mint is measured by mass with a kitchen scale. It's a lot and you're going to think there's no possible way this uses that much mint, but I assure you that it is correct and necessary. You'll thank me.
Remove the ice cream from the freezer at least 15-30 minutes before you intend to serve. How long it takes to soften up will depend a lot on the size of your container, how cold your freezer is, and how cold your refrigerator is. I freeze my ice cream in paper pint containers partially for this reason.
As a "lazy keto'er", I don't stress about dark chocolate. If you want to reduce your sugar even further, I recommend Lily's Dark Chocolate Chips.