They did: Buy an Xperia 10 II or III, flash SailfishOS and the root volume size will be 4000 MBytes. That is how they addressed this issue. Its up to the device porters to utilise the scheme Jolla developed for this, which I comprehensively described in some other Volla specific thread (“topic”) here at FSO.
Until now, I wasn’t couraged enough to follow this howto, because I fear to brick the phone.
Did you meant to address specifically the section 3.3 Increasing the “root” LVM volume size?
Well, at the beginning of section 3.3 I explicitly described how things should look, before one starts altering the LVM volumes: If they do look as described, I see no reason why this section should not be applicable.
But you cannot “brick your phone” (which means that one cannot reflash it any longer) by altering these SailfishOS specific LVM volumes: The partitioning scheme and the content of any other partition (e.g., the boot partition(s)) are not touched by following this section 3.3.
Also I don’t know if this howto is also working on the Volla, it’s written for the Sony.
Neither do I, because I do not own any of the Volla models.
Though IMO, solely the section 1.1 First steps contains mostly points, which are specifically for Sony Xperias.
TL;DR
If you carefully read my “Guide: Installing SailfishX on Xperias”, all sections should be applicable to any SailfishOS device, with the exception of section 1.1.
I happen to own only Xperias, hence I developed this guide on, with and for them, thus I do not claim anything else.
Feedback from users, positive and negative (e.g., criticism) is always welcome, for this guide preferably by opening a new “issue” at Gitlab.
P.S.: I still wonder why @piggz did not increase the root volume size to 4000 MBytes for his more recent ports of SailfisOS, like Jolla did for the Xperia 10 II and III. I already provided this suggestion accompanied with the technical details in some other Volla specific thread (“topic”) here at FSO.
I do see that it might turn out to be troublesome or impossible to increase the root volume size in an fully automated manner when upgrading SailfishOS etc. But to create a larger root volume when creating a new installation image for a new device appears to be quite easy: Just utilise what Jolla implemented.