egui_dnd
... is a drag & drop library for egui.
Give it a try here: https://lucasmerlin.github.io/egui_dnd/
To get started, take a look at the simple example.
https://user-images.githubusercontent.com/8009393/208330770-d9756a13-e3a7-4f99-a5f6-53990b892026.mov