Extract Num type into lightweight SymbolicsBase package?

[LebedevRI]

I'd like to see Symbolics.jl supported in Measurements.jl,
but for reasons, the Num type would need to be explicitly allowed
on the Measurements.jl side, which will require depending on
whatever package providing it. Would it be possible to facilitate that
by extracting that type into a new, light-weight package?

Refs. JuliaPhysics/Measurements.jl#142 (comment)

Thanks!

[LebedevRI]

I think SciMLBase.issymbollike() is what i need.
This brings me to SciML/RecursiveArrayTools.jl#264

Thank you!