Free Pascal on the Mac can be considered mature, you should have no problems with libraries etc. It integrates in the Xcode IDE, so you can do comfortable development. It also comes with a large amount of API interfaces units.

Lazarus is a different story, while useable, it needs X11 to run. While it can produce Carbon executables, Carbon support is beta quality at the moment. However, you only need to worry about this if you have VCL code.