Tom Gewecke wrote:
Could you elaborate on what you mean by that?
No! I don't understand it at all.
Are you trying to customize the popup menu to change or add items? Or add special characters to a laptop touch bar?
I'm just trying to figure out that crazy customization to see what I can do with it.
Open up the keyboard viewer. Click this tiny button in the corner:

That will show a context menu. From there, choose "Customize" to get this:

and I'm like, WTF? Can't figure it out at all. I can add entire keyboards. I can add custom buttons. Can't get any of it to actually do anything.
The only thing I did manage to do was at the top level of that almost-hidden ... menu. I was able to change the appearance from Dark Mode to Light Mode. Because my interface is set to Light Mode and this dialog doesn't respect that, because Apple.