With a recent change that removed dialog in favor of bsddialog, FreeBSD has now retired the last piece of GPL-licensed code in its base system. Although the impact of this change will be minor for …
There’s plenty of benefit in contributing back to permissive projects you use, because you have less maintenance overhead if the diff between your fork and the upstream source is smaller.
Of the ones listed, Apple and Sony have definitely contributed back to FreeBSD. Apple hired the lead LLVM dev and paid him to keep working on it. Sony has paid for LLVM development in particular, but also development of other parts of FreeBSD. Source on the Sony bit, which also mentions that for example Netflix is an even bigger contributor
There’s plenty of benefit in contributing back to permissive projects you use, because you have less maintenance overhead if the diff between your fork and the upstream source is smaller.