Thanks for sharing, Kaede. It looks like this datepicker code isn't compatible with v2, but it does work with v1 inside and outside of Lightning.
Specifically the bit that v2 doesn't like is the
Skuid v2 fields don't use the jQuery UI datepicker, so customization is handled differently than in v1.
Specific use case: You can create a datepicker in v1 that only allows weekends to be selected. Currently unable to recreate in v2. (@Kaede Holland feel free to weigh in on your use case and what you'd like to see here).