Notelet let's you show a sheet with release notes when user updates your app to a new version. It supports plain lists of features (similar to what Apple is now doing in their apps) but also images and videos.
You can configure it to show up automatically on the first launch or using a manual trigger. It also remembers the latest seen version automatically, so you don't need to save anything to UserDefault manually, "it just works".
No third-party dependencies, minimal build footprint, of course, no tracking or other shenanigans.
Supports iOS 17+ and iPadOS 17+.