I have an electric bass guitar - which has strings - and picks up the string vibrations magnetically - so not dependent on the bridge or soundboard.
Typically, the fundamental, though strong, is weaker than the second harmonic.
I figure it is just how strings prefer to vibrate.
I (finally) intentionally produced a pluck with a higher fundamental, for the purpose of observing the harmonic series, but it wasn't easy:
View attachment 102762
I'm not sure if the electrical pickup is "flat", and it has knobs to perform some filtering, so, my observation is not scientifically rigorous.