I'm usually not an Ai shill, but I found Fable to be the first LLM that could actually provide useful feedback on a KiCAD PCB design. I paired it with a KiCAD MCP, but it tended to reverting to raw KiCAD scripting. If you ask it to review a PCB design, and provide feedback relevant to PCB design best practices, it will probably give you something useful. I wouldn't trust it to do a full design, but it's pretty good at finding issues. I'd add a few clauses to the request regarding checking components against JLCPCB/PCBWay/etc available components, as well as checking copper layer thickness and distances from the main components to the supporting components.

I did this as an experiment on my current project and it found a bunch of minor, non-critical, but completely valid problems with my deisgn.