Even if they contract it out, at $350/hr (which is not a price that would raise any flags), that is less that $750k. Even with a fancy office, couple of laptops and 5' monitors, this is less than a day at the bombing range or a few minutes keeping an aircraft carrier operational.
Even a team of 10 people working on this - the code and social aspect - would be a drop in the bucket for any nation-state.
This is only evidence that libsystemd is popular. If you want to 0wn a bunch of systems, or even one particular system but make it non-obvious, you choose a popular package to mess with.
BeOS isn't getting a lot of CVEs attached to it, these days. That doesn't mean its good or secure, though.
Even a team of 10 people working on this - the code and social aspect - would be a drop in the bucket for any nation-state.