Plots in Julia is installed on my heavily guarded Linux distro (if it were not ‘using Plots’ would already raise an error).
I thought my post explained it:
julia> using Plots
Julia> plot(rand(23))
will throw the errors:
QT not found and the GKS error message (as shown in my original post).
(It would work on my OSX Ventura and my Macbook but this is beyond the point because here I am my own super user and can always make sure the BSD is up to date with various homebrew hacks).
I am not alone: Problem with Qt dependency of Plots.jl