Here’s the thing - Sangoma OS 7 is already unpatched. They are not pulling the CentOS updates into Sangoma OS for months; I don’t think I have seen an OS update since last year, maybe farther back.
As an example, a fully updated SNG 7 OS has kernel 3.10.0-1127-19.1 from 2020. There have been several kernel patches released since then, as well as numerous low level libraries: CentOS security alerts [LWN.net]
So for whatever that is worth - “end of June” is kind of meaningless; if you care about patches, you’re already naked 
My opinion is just wait and get on Debian 12 with FreePBX 17 as soon as you are comfortable with its stability. Then the OS and Sangoma’s management of it will not be a concern; you will be getting the OS directly from the source.