PathDB (debugger) has been ported to FreeBSD, but I thought others
around here may have some (mild) interest.

Summary:  x86/x86_64 debugger with the goal to drop-in replace gdb.
We recently finished some heavy refactoring and now focusing on
improving performance, robustness, scalability (clusters/multicore
systems), DWARF4, OS portability and supported targets.  PathDB
has a library based design with a CLI interface doing direct function
calls.  Using C-bindings it should be fairly trivial to extend or
add a new front-end in python or other scripting language.