Is it possible to build add-in that will add section with button in detailed view of an event in calendar

Question

Hey folks!,
I'd like to start building an add-in that would be able to add extra section in the calendar event detailed view like on the screenshot below.
The section will be visible while adding new event and also while displaying details of existing one.

The section will probably contain a button/action so there needs to be a way to have communication with my own server.
Is it possible to create "add-in" to achieve it?

Here is the screenshot that shows a mock-up of my goal.

Can I use the same method as described on:

• https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/online-meeting
• Does the example linked above work only on mobile iOS / Android?
• Is there a way to create an add-in that will extend the detail view of the celendar's events on all clients or most clients: web, mobile, native windows app?

Best,
Samoyeet