

If you want to get involved in open hardware, a good first step would be to learn KiCad. It’s is used to create electronic circuit schematics and turn them into printed circuit board (PCB) designs. Here’s a pretty good tutorial to get started with it. Please ignore the instructor’s obnoxious Ronald Reagan quote in the second episode.
A PCB is usually not enough, of course. You should also learn FreeCAD so you can design the mechanical aspects of the hardware, whether that be a simple enclosure, or a more complex system with multiple moving parts. Here’s a good FreeCAD tutorial.
I mention KiCad and FreeCAD specifically because they’re both free and open source. You can check out this awesome list for a list of cool open hardware projects and learning resources. Two projects that really stand out to me are the LumenPNP pick and place machine and the Voron 2.4 3D printer.
For in-person groups, see if there are any makerspaces/hackerspaces in your city. That’s where you’ll most likely find like-minded people.



You are right that this sort of project should not be attempted by a beginner. It would have to be a collaboration between several experienced engineers. OP should not attempt this alone.
My hope is that by the time these surveillance systems become mainstream, OP has enough experience to collaborate with others on such a project.
And since you mentioned throwing Arduinos at cars, I thought I’d mention that there’s apparently over a thousand cars that have had their ECU replaced by a specially-designed Arduino. I guess there’s several open-source ECU projects out there. Might not be street legal in all jurisdictions though 😅