Nothing set yet - every feature below is falling back to its own default. Set one or more features, or import an existing policy, to build a header.
A feature you haven't set isn't unprotected - it falls back to the default shown against it. Setting one only matters where you want something other than that.
This header sets the ceiling for embedded frames as well as the page. An iframe's allow attribute can only narrow what this header permits - it can never grant a feature the header denies. It works the other way too: naming an origin here is necessary but not sufficient, because a cross-origin frame also needs allow on the <iframe> itself before it gets the feature.
Report URI can collect Permissions-Policy violation reports as your policy runs in production, so you find out the moment something is blocked unexpectedly - not the next time you happen to check.