My apologies no-one is answering your question. I took another look if I could come up with a better answer than in the BinaryBuilder related issue but once more came up empty handed. With the recent interest in CmdstanR and CmdstanPy, which pretty much take a similar approach as CmdStan.jl, I’d hoped broader interest would emerge but haven’t seen that yet.
I wonder if asking this directly on Stan Discourse is a possible next step. I think with JuliaPackaging Julia might be in a better position to solve this issue. I’ll link your question above (C++ & make) to JuliaPackaging/Yggdrasil ( https://github.com/JuliaPackaging/Yggdrasil/issues/1023#issue-617171438 ).