We presume what we search for on the internet stays private. But you might be leaking all of your internet activity through something called a DNS request. I...
The best way to ensure that hardware is compatible with pfSense software is to buy hardware from the Netgate Store that has been tested and known to work well with pfSense software. The hardware in the store is tested with each release of pfSense software and is tuned for optimal performance.
For home-built solutions, the FreeBSD Hardware Notes for the FreeBSD version used in a given build of pfSense software is the best resource for determining hardware compatibility. pfSense software version 2.6.0-RELEASE is based on 12.3-STABLE@ef1e43df92c6. Another good resource is the Hardware section of the FreeBSD FAQ.
Have you read the pfSense documentation, you do need a set of compatible hardware so the firewall becomes functional: