MrEd : the Mixed Reality Editor
This is the source to a visual editor for mixed reality. It is built in react and should be compiled and put on a webserver before using.
You may want to start by trying a live demo on Glitch here. To go further you'll want to remix the glitch itself and edit the ".env" file and set a password. Then make sure you login with that password inside of MrEd (when running your remix of the glitch).