For Plots.jl or Makie.jl or other (non-plot code) this might help:
to enable PyPlot showing properly after it was baked into the [system] image add
I was looking for another project which already has some custom system images pre-built for you (e.g. for Makie.jl if I recall and JuliaSyntax.jl). It wasn’t yet announced last time I know, just be aware that there’s a third project, but that top one seems similar.