Creating additional firm-wide holiday options

I would like to be able to add different holidays as “unavailable” within the holidays section than what is currently offered.  The ability to manually add them at a firm-wide level is ideal, but if that is not possible, perhaps the community can come up with a list of other regularly-used holidays that aren’t necessarily federally recognized.  I’m based in the USA, so for example, Good Friday, Passover, Eif al-Fitr and Eid al-Adha, and the day before Thanksgiving (or the week!).  We don’t currently have a calendar solution (Outlook) that allows us to easily push company holidays to everyone (and not just as a shareable calendar, but to actually put it on everyone’s calendar as time off) in order to keep appointments from being booked over those dates.