Is this setting in about:config really not accessible?

Hello,

I would like confirmation that the setting
“extensions.webextensions.restrictedDomains” in about:config is not accessible via the API types.BrowserSetting with the get() method, I get an extensions is not defined message when I try, which seems strange to me because there is also a levelOfControl variable, which could have been given as “not_controllable”. That’s the only option available if I’ve been browsing MDN correctly, right?

I’m totally new to the field so I may have misunderstood some technical notions, so I prefer to ask.

Thanks for your help and time.

Almost no about:config settings are exposed to extensions as BrowserSettings. Most of the ones available are exposed at
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/browserSettings

Security relevant configuration like the key you’re asking about is especially not exposed. There are very good reasons those domains are restricted to avoid privilege escalations.