Overall Microsoft has really embraced open source. I think they’ve basically pivoted to trying to own everyone’s hardware (via everything becoming a part of Azure), so tight control over the software no longer matters to them.
Not sure about Apple. I haven’t noticed too many open source initiatives from their end tbh. Their open source work is either simply because they bought/forked a legacy FOSS project (CUPS, WebKit, BSD), or it’s very developer focused (FoundationDB, SDKs for building apps on Apple hardware). They don’t really have open source products like Microsoft does.
I would say your assessment most fits Google actually. They really seem to have no clear plan one way or the other when it comes to open source work. Seems like a very “every team for themselves” company to me.