The responses don't have to be strictly NixOS or Linux specific as I expect the general process to be very similar.

I never hardened a system before so I'm not sure what things I should be focusing on and what solutions are out there. I'm hearing a lot good on SELinux and apparmour but but those sadly aren't supported on NixOS. Recently I set up adguard home with somewhat strict blocklists and SearxNG to take control over my web searches. In the coming days I intend to set up wireguard and a VPN in my config and I also have some firefox extensions for blocking ads, trackers, JS, port scanning, etc. but it all feels surface level and I don't know where to take things from there. What are you guys doing with your setups?

Usually I prefer to never ask questions and look things up myself but reddit will soon block everything with a login wall and that's where I get most info from so I'm finally giving it a shot. :p