after adding this library to your engine. and new tool will appear in your engine, called Vertex Snap. add collider to that object! (otherwise tool won't recognize where the vertexes are or if you are even hovering your mouse over it) with that you can select object and while holding left ctrl, you can snap this object to other vertexes.

works with different sizes of objects, different rotations.

it's not perfect! but i just tried it cuz i missed this feature from godot. inspirated by godot addon called Snappy.