You'd still need a spec for this because of cross-language considerations, but that doesn't make it a bad idea.
i.e. if an app is written in javascript and running on mac there are potentially 4 different languages all running inside the executable that need to cooperate to handle the BOM signal and report their deps - C/ObjC, Swift, C++ and JS. Presumably you'd want to report not only the native libraries being used in the process but also things like npm packages.
Good point on that. The bom signal could be relayed. E.g. for a runtime, or multi tenant app, the parent runtime would relay the bom signal.
Presumably the runtime would have the loaded symbol table, which could be used in lieu of a BOM summary.