A WIP for this can be found in wip/buildid, it will include the buildid in the heaptrack file. But for interpreting, it isn't enough to just load the debug file only. It has to be used in addition apparently, which isn't possible without patching libbacktrace like is done in vogl.

At this point, I think it may be a better idea to port away from libbacktrace and use elfutils instead (esp. libdw{,fl}). We could even use that for unwinding, getting rid of libunwind, or at least adding that as an alternative to libunwind for platforms where elfutils is better (faster?) than libunwind.