@user202729 gdb takes control over another process. That cannot be allowed in the sandbox, as two different sandboxed processes are not supposed to be able to interfere with each other.
@Dennis I asked about Object Pascal earlier but you never responded. Object Pascal is different from Pascal in the same way Objective C is a different language from C, but the fpc command is able to compile both languages. To compile Object Pascal, replace fpc with fpc -Mobjfpc in the wrapper.