Just another step towards Ubuntu or another proper linux distro to take over the phone space.

Ubuntu actually pioneered the domain with Ubuntu Phone, and then abandoned it. It's been taken over by UBPorts, a community effort, with Lomiri for it's graphical environment. I don't know these much, as I think they don't let you run regular Linux apps.

There are many linux mobile distributions, I think the most mature / widespread ones are Mobian, PostmarketOS and Manjaro. And UBPorts of course.

Mobian has been upstreaming most of its work to Debian proper, which is cool. I'm using Mobian but there's not much Mobian-specific stuff remaining. I think they nailed the development model.

SailfishOS is totally usable. It is not as open as some others, but they get more stuff to work

How are they, as a company, with all the Russia shenanigans (trade bans, etc.?)

From what I have been able to determine as a user, the sanctions have been a big blow to the company, but they are still able to operate in Western countries and are also seeking partnerships in China. We'll have to see if they can pull through and keep some part of their business profitable.

Yes, I always forget about it (because I'm not interested personally. The way I see it is that if I want a mostly open source mobile OS but with some proprietary blobs, Android is just fine. I just can't justify using SailfishOS).

I strongly disagree. It's just another step towards other open source apps taking over those two use-cases on alternative Android systems. AOSP is still open source, and maintained by Google. So this doesn't seem like a big deal to me, like at all.

I feel like people tend to really under-estimate the difference between "proper linux distros" (why "proper", btw?) and Android. Android was designed for smartphones, good luck catching up with "proper" distros.