> Your examples are almost entirely focused on the tools to build software
All save of the things I listed aren't just a tool used by developers and have user-facing components, but yeah: that's my bubble. However if most of our tools, libraries, and technologies become open source, then inevitably end-user software will become more open-source as well.
> All consumer operating systems with non-negligible marketshare are proprietary (including android)
That's the purist way to look at it. I can understand it when it comes to free-as-in-freedom software vs. proprietary software, but for open source vs proprietary it doesn't make much sense.
It is a sliding scale and it matters how much of the software stack someone is using is open source software. If you open some random "SaaS" website nowadays, most of the code running on your computer will be open source, as will most of the software running on the remote server. The only things that aren't open source will be whatever the SaaS company hacked together on their open source stack, and possibly the operating system your mostly open-source browser is running on. In the case of Android most if not all of the code executing in that moment would be open source as well. Take further apart their JS blobs and it's just 90% libraries they grabbed from NPM. Take apart their server side and it's more of the same.
The point is that the amount of open source code people are running is increasing. Saying "but a lot of software has closed-source parts!" is being blind to the change that occurred.
If you just care about OSS as opposed to FOSS, you likely either care about being able to audit (even crowdsourcing it) what you're running on your computer, or you simply believe that it is the best way to develop software. In recent years we've had both a better shot at auditing what we're running as well increasing collaboration between software developers.