Gridstack is a great tool for building complex grid layouts with drag and drop for specific use-cases.
Puck is for creating a complete page building experience, which includes not only drag and drop, but also user input via fields, viewport previewing, APIs for fetching data, etc.
Gridstack also provides it's own grid system, whereas Puck currently is unopinionated, supporting any component library that uses `display: grid` internally.
I'm not aware of anything. You could potentially use Puck directly if you wrap your Angular components inside React components for the purpose of editing, and build a custom version of `<Render>` that walks the data object and renders straight to angular.
1. You can override a bunch of stuff using React-like APIs. `renderHeader` allows you to take over the header, and the plugin API allows you to wrap the root of the preview content page and take over the fields area on the right hand side. We don't yet support full take-overs, but we'll continue to work on these. Plugin API: https://github.com/measuredco/puck#plugins
2. I think you should be able to mimic a bunch of the behaviours. The main missing piece is multi-column support, which is landing soon via the `nested-dropzones` branch: https://github.com/measuredco/puck/pull/37