The new beta of Gestaltor with the glTF editor is available for download in a free summer but there is also a paid option for those who want to take 3D development seriously.
It is possible to work directly in the program with the format and also use all Khronos extensions.
The interface is easy and designers can here edit and compose, combine and even optimize 3D files in glTF that were created in other tools, and then prepare them for implementation in other 3D engines or viewers.
The editing of the files is completely visual, and in the tool you can change textures and materials, and change the environment completely.
Gestaltor was developed by UX3D GmbH and works on Windows 10, Ubuntu 20.04 and MacOS 10.15, but pay attention to the technical specifications, which are demanding.