Admins often need to set channel policy based on target, and this data is provided to the channel policy, but there is no convenient rule for it. At present, admins have to use a somewhat obtuse rule like:

bool target && match target foo-* :: use foo

It would be nice to have a dedicated (and documented) target rule, so that this is easier for admins to figure out.

Secondarily, we should also consider having the buildtag rule deduce from provided target data.