One additional suggestion I might make is to allow you to report the post to your own instance admins but not the host admins. This would be useful for when you want a post to be hidden or an instance defederated and you don't want to also send your identity to the instance you're reporting.
This might be used for:
Reporting spam coming from an instance that is unlikely to delete it.
Reporting CSAM on an instance that supports it.
Reporting hate speech on instances that believe hate speech is covered by free speech.