Welcome @jurnix! See the ongoing discussion here. It’d be great if you can join and provide your feedback there.
As of right now, there’s not much consensus on how to best treat dates and times in stdlib. They are certainly in scope.
In the meantime, datetime-fortran is still easier to install than stdlib, so if you’re working with stdlib already using datetime-fortran should be no extra burden–you can install it using CMake, autotools, fpm, or simply drop-in the source file in your project.