niemimat
Hello everyone, and thanks a lot for this forum (first post here :)) !
And thanks a lot too niemimat, I faced the same problem you and Nobrac did and you helped me fix it whereas I was unsuccessfully trying several things before and did not know where to look at !
So, Pixel 6a too, with GrapheneOS just installed (Android 15, build 2024102400), and unable to use SMS Import / Export (nor Fossify SMS Messenger either) because of this weird message :
When you go to Settings > Apps > [app name] and try to add the SMS permission (that is grey), it warns you with a message "App was denied access" and a link "Learn how to allow access" that doesn't point anywhere and open nothing, so that I didn't know where to look at.
--> Maybe something could be changed in this message so that people know what to do ?
Then I found your solutionnienimat and tryed it, but at first I didn't find the "three dots" in the Settings > Apps > SMS Import / Export in the top-right corner, instead I had an icon (square with an arrow) opening the app.
I had first to allow the "Sensors" access in "Permissions", then go back to "App info" where the icon had changed to the three dots with the "allow restricted settings" option you talk about.
Then I was able to go back to "Permissions" and to allow the "SMS" access just like you did (and to turn off the "Sensors" permission, it is unnecessary after that).
I have a last question about all this, once I gave this "allow restricted settings" permission to an app, how can I take it back ? Because after that, if I I turn off the "SMS" permission and launch the app, it simply ask me to "Allow SMS Import / Export" to send and view SMS messages?" and it turns on, there isn't this "security locking" anymore.
Thanks a lot again and have a good day everyone !