is there a way to create a Date constant from year, month and day?
No, because the bizarrely-named Date type isn’t a date, it’s a time-point. Everywhere that I use Date in my code there’s a comment saying “actually a DateTime”.
If you want to represent a date (only), don’t use Date. I suggest writing your own type that contains either year-month-day fields or a Julian Day Number.
I'm used to Python which has both naive and aware (of time zone) date time values.
Does Swift have a naive date time concept?
There is also DateComponents.
You’ll probably get frustrated by not having exactly the combination of features that you want, and unless you are constantly passing these things to and from Apple APIs, you’ll end up writing your own replacement.