Group calendar web part visible to entire organization

Hi CW_213,

I would suggest just using a traditional SharePoint Calendar list for simplicity's sake as I believe the Group Calendar is designed for more collaborative sharing.  I'm hoping there will be some announcements at Ignite next month in regards to modernizing the SharePoint Calendar list template, but even if not - you still have the ability to use the Events web part on modern pages to display calendar items from the traditional list.  Once you set up your calendar list, you can just assign permissions just like you would with any other SharePoint list or library.  In addition, the traditional calendar gives you the ability to customize the categories to align with the examples you gave in your original post which you could then use to create custom views and filters down the road if you wish.