Is there a camera technique to visualize currents like in a thermal view?
Schlieren for magnetics or something?

@marble Yes, you can use the Zeeman effect to derive the magnetic field from visual observations. This is how, for example, the magnetic fields in the sun's corona is mapped:

https://doi.org/10.1126/sciadv.adq1604

@datenwolf I don't plan on having my circuits generate this much of a magnetic field :o