FWIW Free Pascal's FCL has the fcl-passrc package that provides units for scanning FPC code, building syntax trees, resolving identifier references and writing/formatting source code.
Free Pascal comes with pas2js which "transpiles" Free Pascal code to Java Script and is written using fcl-passrc so it should have enough functionality to parse most FPC code.
Go neither, but parsing and AST are in the standard library, and code generation is in the standard build process. All it requires is an (ugly) comment line in your source code. So you've got decent and standard tooling. No make magic required.
Free Pascal comes with pas2js which "transpiles" Free Pascal code to Java Script and is written using fcl-passrc so it should have enough functionality to parse most FPC code.