The files you will deliver to the client are basically HTML, CSS, JS, GLTFF, BIN and media folder.
All of the settings are can be changed by editing the basic HTML type files. They can change the logo, the loading bar color, the size of the logo, the background color, etc.
The Settings Panel in the Application Manager is just a super simple way to quickly edit these files so you don’t have to go into those files and do it yourself.
The client could of course buy a license to use that tool, but its not worth it if they are only changing those things. If they are going to take your project and insert it into a website they are should have the skills to quickly edit these things. If they don’t have the skill set….you should sell your services to them to make the necessary revisions and get them a new file.
If I were you I would send them a sample file…and they can go play with it until they figure it all out. If they have the skills…should take therm only a few minutes. If not sell a maintenance agreement