Not a lot of people know this, because it doesn't seem to be documented anywhere except this Japanese tutorial from 2020, but you can use Editor Utility Blueprints, UEditorUtilityToolMenuSection and UEditorUtilityToolMenuEntry subclasses to create Blueprint menus and menu entries to customize Unreal Editor!
Don't forget to turn on Display UI Extension Points from the Editor Preferences -> General - Miscellanous section in order to see all the underlying names of menus in Unreal Editor that you can then use to extend the menus with your own submenus, tools and scripted actions!