Which engine/framework to choose for developing UI for IoT?

Question

User interface

I make electronic modules for a smart home. I want to start building a server that will manage all of these modules and also be a GUI server. The main task is that any user can edit the interface for themselves, being not familiar with programming. Example: the editor window opens, on the left is a set of elements (buttons, sliders, labels, tabs, etc.). On the right is a window that will then be the main interface. Using the drag'n'drop method, the user drags elements, changes their properties, such as color, size, and associates the element with the corresponding module. The issue of the backend is not important yet, the main thing is that, in principle, it should be possible to fasten it (the language is also not important). The most suitable solution for my vision of the task is Flowboard based on Totaljs. But the application is quite raw, little functionality in terms of UI (the backend is good there, I don’t argue). Perhaps there is something similar, some kind of framework? There is a lot of work to be done, as for enthusiasm, I would like to make my life a little easier. Writing everything from scratch is almost an unbearable task for me. Any ideas that meet the requirements are welcome, and the more the better. Thanks in advance!