So it seems like the challenge here will be to get buy-in from all these different parties that they should support some common format?
I guess the request to the committee would be to bless one in some way (some sort of non-standard, but standard-adjacent document? with some form of the weight of the committee behind it) in the hopes that that will help add more weight to the feature requests on these tools to add support for this format?
Yes. The idea is that SG15 could drive interoperability on specific scopes (particularly GNU/Linux, but possibly applicable to any POSIX system), maybe via a Technical Report on a specific format that could be used by build systems, GNU/Linux distribution maintainers, etc.