Your enquiry covers a lot of the same as this older thread, Attempting to upgrade Terracube 2e from version 1.0 to 1.1 (2020 model).
A solution is introduced by @alexis (/e/ support at leader level) at post #12:
@ecs observers at post #15 re the update offered to him
At post #16 are specific instructions. I think you already read the links provided by @Manoj – as you observe, the Gitlab issue seems still in hand: https://gitlab.e.foundation/e/backlog/-/issues/5766. My reading of this is that applying your mentioned OTA update would not be a fix.
In other linked threads we read of a proposal sending an SD card to users who would prefer the fix provided in this way, but as far as I can read this is still “in progress”.
As yours is a purchased phone you can register for further help by email to helpdesk@e.email.