You'll first have to parse the SAS code, then output python or some other intermediate form.

Does an open source parser exist?

Golang did a C to Go transpile, there are some articles and maybe a talk on it out there. It likely won't be 100% perfect, so you will need tests to verify correctness.

I have a tool that isn't open source yet, but it could be quite useful if you can get SAS to an AST in json or other data format. Hit me up if you'd be interested in talking about that option.