It would be helpful if InDesign could show which character sets are protected. According to the motto "Don't make me think". Currently you have to check each character set manually. That is a bit tedious. See screenshot.
Well, yes, I do agree that a tabular representation of the Information of every used font would be helpful. I would not use a lock icon. Just the written information. And a sort function would be cool as well.
Just like we can customize the Links panel with tabular info about "Effective PPI" and other properties of an image.
You've identified fonts in Adobe Fonts. You want a lock. Why? In what specific sense do you mean "protected"?
(The usual meaning for a font would apply to font licensing rights, such as not being available for PDF embedding. I think you mean something different).
I want to know, which (Adobe) fonts will not be exported by "Datei > Verpacken" (File > Packing (?)). Where I gat the .indd, .idml and all images plus non-protected fonts. When I know, which font is protected, I can subsitute these by OFL fonts before exporting.
I think, that place in the screenshot would be a cool place to show which font is protected/locked by Adobe.
I realize that English is not your first language but "locked" is the wrong word to use. That indicates that would not be useable in at least some situations. That is not the case.
Adobe Fonts are embeddable and licensed for any output that InDesign supports. The only "restriction" is that they won't be packaged. There is no reason to package them anyway. If you're sending the file somewhere the recipient would need a Creative Cloud subscription, too, and that would include the access to Adobe Fonts.