-
As firmware is released for say a 2 year old device, the person who built with the latest available firmware cannot say for certain at that point that firmware upgrades have ceased.
-
We can take as guide that most manufacturers (notably different Fairphone) only generally continue firmware upgrades for 18 months to 3 years. There will be many exclusions from this over simplification
-
We each have to do research the latest vendor firmware upgrade before installing /e/OS on our device.
What if users were to share the Vendor SPL (security patch level) of their researched and correctly running /e/OS device. Settings > About phone > Android version > Vendor Security Patch Level.
We could then put together such a list as you propose. I also proposed and contributed to such an idea, rather hidden away in this editable post Upgrade Galaxy Tab 5e from "r" to "s" - #4 by aibd.