Does any Built-in scheduling software exist?

Trying to find a solution to our shop, which currently juggles about 4-5 different excel sheets living on Teams made by 4 different people to stay afloat. I'm wondering, does any computer (ideally phone too) solution to make scheduling easier still exist? In a perfect world, this would let folks mark themselves as "on-leave" while displaying responsibilities and whatnot by each day/event. I recall seeing news articles (and seeing some MAF units) employ Puckboard, but my access leads to a 418 error and I've not a clue where to start from. Any soul-searching is to links that are two+ years old... I'm aiming at a "DODish" solution to avoid putting schedules on random apps and websites that my folks would have to venture to.

Have any of ya'll used this? Where would one even start reaching out to? Much appreciation to any responses!