[trott]

How do Maxima and SymPy compare in terms of capability, features and speed (native, not WASM)?

[rockybernstein]

In terms of features, I imagine they are about the same. Here is why I think this. Maxima's function organization seems to follow and refers to the NIST Digital Library of Mathematical Functions https://dlmf.nist.gov/

Mathematica and Sympy also seem to follow this organization.

My take: I blame compatibility on the NIST Digital Library of Mathematical Functions.