I go for Arrow when I want anything beyond the basics. This looks pretty interesting, not really because of the greater coverage in edge cases, but because while it has a Rustified mode, a pure Python mode is also available. If I do use whenever, I don't have to worry about having something else or falling back to datetime if I want better datetime handling in a project on my phone, or in some other environment where the Rust toolchain is non-existent or problematic. Kudos.