Once you’re working with a project plan, you probably want to pull key milestones out into your system calendar so that you can get reminders, forward the calendar events to others, and so forth. This shortcut finds all events tagged with “milestone” in a given project, creating all-day events in the system calendar for each one. Here’s a simple example input:
Afterwards, they appear in Calendar, like any other event:
Download from this iCloud link.
Here's how it looks in the Shortcuts app: