How to create a shared company calendar for time off and holidays?

Wow. This is old... 

Here's the solution I've come up with. It's not ideal. 

TL;DR: Just use Outlook and SharePoint. Make sure groups are displayed in Outlook. Add Group Calendar web part to SharePoint. 

The first thing we had to do was (compromise 1) ditch the hope of accessing the calendar outside Microsoft 365. The calendar is only accessible in Outlook and SharePoint. 

I think one big issue I had was that Groups and their calendars were not being displayed in Outlook by default. I had to use Powershell to enable this. https://learn.microsoft.com/en-us/exchange/troubleshoot/groups-and-distribution-lists/microsoft-365-group-does-not-appear-in-outlook#resolution 

Company Communications Calendar

We have an org-wide Company Communications Group/Team with a calendar in Outlook. I can easily create an event like Memorial day and have it repeat every last Monday of May. 

How to get this in SharePoint? You can add a Group calendar web part in a Sharepoint page. However, (compromise 2) it only shows as a list, not a calendar. 

I guess this solves the larger issue but at some point I decided I wanted the staff calendar seperate.

Staff Calendar

I have another Group called Staff Calendar. For this, I built a Birthday PowerApp that I've embedded in SharePoint and a PTO PowerApp that I uploaded to Teams. Both of these have PowerAutomate actions upon submission. 

• For a Birthday, there's an action to create the event in the group calendar and then update its properties to repeat every year on the same day. 
• For a Day Off, there's a workflow to request a day off. This workflow adds an item to a SharePoint List, prompts the supervisor in Teams for approval (logs the approval results in the List), adds the PTO to the group calendar, adds a record to the employee's folder (in SharePoint), sends an email to HR with links to the approval record and calendar event, updates the List with links to events and records.  

So, if you're keeping track; there are two group calendars in Outlook and two web parts in SharePoint - which are lists, not grid-like calendars. You could do it all in one group but I didn't. 

I guess the other big fix for this was creating apps for users to submit information. This way, instead of asking people to give me their info or having them screw with the calendar, I have a workflow doing the work and keeping things consistent. I wouldn't be surprised if you could pull this together with CoPilot or something now. 

Hope this helps someone, four years later.