Disable specific apps access to stock browser?

With a productivity lock in place with an access code that is set by someone else, the phone user cannot directly open the "stock browser" unless Android asks: > Sign into public wifi network if I happen to connect to such a network that requires signing in. That is as intended, At the same time I am trying to disable the user access to the "stock browser" from any other app such as Slack. To be clear: Slack has a button that disables opening links with the "stock browser", but that does not prevent the user access to the "stock browser" as the user can go to settings>advanced settings>flip that button that prevents access. Therefore I have the following **question**: *How can one prevent certain apps from opening the "stock browser" in LineageOS 14.1?* Currently my options consist of: 1. Modifying all apps to such an extend that that function is not possible to re-enable once it has been disabled. 2. Finding a setting that allows only specific apps to open the stock browser. 3. Finding an app that enforces such control settings. Neither of the 3 approaches have yet led to successful blocking of "stock browser"-access.