You could make a list of holiday dates and put them into an asset, then use that asset in your automation. Most holidays are simple, though - 1/1, 7/4, etc.
The tricky ones are Thanksgiving - you’d have to calculate if it’s the fourth Thursday of the month.
Easter? Basically impossible to calculate unless you’ve also got a Moon phase chart available to read.
In the end, making a list of holidays for the current year and updating it every year is about the only reliable solution I’ve ever seen. Of course, you could make your asset contain every holiday date for the next 50 years if you wanted, then never have to touch it again.