The Airthings View Plus is a good one. It has high quality (for consumer) particulate, CO2, VOC and Radon sensors and a good interface. Also tracks temperature, pressure, and humidity for completeness.
Practice like you are learning a musical instrument or chess. Break it down into very specific subskills (like a specific chess endgame or guitar picking technique) and practice those in isolation in addition to your usual practice. Also find a coach if possible.
Feynman diagrams are a representation of an integral so moving beyond them is a question of reformulating the mathematical basis of physics.
There is some work in that direction (look up 'Amplituhedron') but overall it's not that surprising that physicists are using computers to do the same math with much more precision than they could before rather than shaking up the fundamental mathematical tools of their field which have stood since the 1600s.