Catch-All rule to add "Access-Control-Allow-Origin: *" to all responses?

The title says it all, really. Would that be possible?

We used corsproxy.io for a while to import RSS feeds into Grafana; but that isn't working anymore unfortunately... So, we decided to try hosting a solution ourselves. And thus, I found this project.

I even got it to work with our firewall's CA, but we now get no CORS back at all, which Grafana is mad about o.o

Any idea?

Thanks and kind regards!