Redirecting all blocked traffic to a custom block page

I have seen some old discussions on this and wanted to check if it was possible.

Implementing the installation of the root certificate on all the devices is not an option, for reasons I shall not explain. However, I want to let the user know that the page was blocked (not just show an indecipherable error message) on purpose. I would like to change the mode for all the selected services/filters from BLOCKED to REDIRECTED and have them point to mydomain.com/blockedpage.html

I understand it is possible for SERVICES. However, ControlD has not implemented this for FILTERS. May I ask if this is on the feature roadmap, or if there is some hidden way to enable this (e.g. via API, not via GUI)?

Is that possible for FILTERS? What are the concerns / limitations with this approach? Thanks!