I think it is more if they will encourage any use outside of the control of Google. Or if they, like with Android where they illegally obstructed companies from doing so, will even discourage it.
So, it is technically "Open Source", but I am not sure I would call it "Free software" in the spirit. Especially the permissive license, which gives developers free reign over their forks.
I really like being able to get kernel sources from various phone vendors, and that's what enables projects such as postmarketos or lineage (though lineage is less concerned about getting the kernel sources/upstreaming, it seems). I just wish there was an anti-tivoization clause in the Linux kernel license.
On the one hand, it's great that old phones see some updates. On the other, it's terrible that Google used it as an excuse to reject and weaken the very ecosystem that propelled them to where they are.
They've made some efforts to improve the ease of updating older phones for both OEMs and users, but they keep key components locked down.