Field validation should be extended to date fields to enable user to disable past dates, weekend dates, and company holidays (in a data table).
Released May 2020
This has been added to our next major release, planned for May 2020. The initial release of this will provide a lot of power and flexibility for date validation, but it will be more technical to configure. We plan to provide several common examples in help to make it easier and will also plan a subsequent release for no-code configuration of common date validation needs.
This was released today! You can use Expression Validation to validate dates. You'll see several examples in the help article.