Looking to Avoid HD Firmware Malware & Bad USB

Malware on hard drive firmware and bad USB has me greatly concerned since they are extremely difficult to detect.

I was wonder if running Linux on an SD card on Rasberry Pi or alternative would avoid both issues.

I was considering install PwnPi, a Linux-based pen testing drop box distribution, but wanted to know if I would it would buy me these maiware-free benefits. Thanks.