Most of this is not related to the claim and is more tangential discussion about things you like that run on the linux kernel, now, there is nothing wrong with that, but I must emphasise that none of what you describe is a part of the criteria for what constitutes a linux distro. A linux distro is an operating system using the linux kernel. Android fits that criteria.
The policies and applications running on top of or in the linux kernel do not change its distro classification. Lacking root access is a massive step forward for privacy and security. Root access is insecure and a hacky shortcut to proper functionality.
Sure, we can have different opinions on what makes a useful Linux distribution. Either way, you can't install Ubuntu Touch on just any phone. That Volla supports that alongside their AOSP derivative gives you more options on how to use the device; it's worth pointing out to potential buyers as a bonus on top of running Android only