Bookmarks is a useful feature of Obsidian, but it’s not possible to natively add an item to the contextual menu on bookmark items or groups. Instead, the developers have to resort to dirty hacks like injecting a trigger event, which is not reliable.
Adding the access to contextual menus on bookmarks as a native API feature would make it possible for developers to create apps that would help users operate on those bookmark items in bulk, perform analysis, etc.