Linux mint has apparmor built in

[OPNenthu]

Cool, you have a trusted network of some kind.  You use segmentation.

I presume most are and I think that it is much more effective than apparmor on the client.

I challenge the idea that the backend is "open and everything is allowed," because there shouldn't be access to the backend.  Only if there is an exploitable vulnerability in one of the services, which is in the realm of possibility (however unlikely).  I want to give OP some credit, despite the other wild and alarmist claims.  I don't buy that their OPNsense is getting hacked like this without receipts.

[Patrick M. Hausen]

I don't buy that their OPNsense is getting hacked like this without receipts.

Me neither. Also those "50 attacks per hour via browser" is probably just the browser downloading a truckload of assets and ads rendering a perfectly normal 2025 web page.