Most likely Windows and UNIX clones would have kept taking their pieces out of BSD, after the 386BSD lawsuit was settled without any other alternatives to reach out for.
You can see this from how much Playstation OS gets upstreamed into FreeBSD.
If you want to talk GNU/Linux, then we can switch to Android and ChromeOS, which have indeed done several contributions, in fact many of those left out weren't accepted.
With Android, Google wanted to give their changes back, so they were able to use GPL-ed code. They would give the changes back without GPL too. You can see that with non-GPL-ed projects they contribute to.
Several Google contributions were taken, just not 100%.
One notable contribution was cleaning up the kernel from all VLAs, the fortifications of several modules, some cleaning outcomes from clang compilation support.
Or the ongoing efforts to allow Rust drivers.
With Sony there were 0%.
You're stopping your reasoning at the numbers: some contributions from Google, none from Sony. (At this step you're also ignoring contributions to FreeBSD from companies that do contribute back, but whatever.) The big picture would be understanding why GPL wouldn't affect that situation.