Firmware expectation/requirements

At least one user within my LG phone community has had an issue with firmware versions during /e/ install. Before I decide to give my best shot at it. I need these two questions answered:

How can you view beforehand 1. the TZ firmware version /e/ is basing the build from and 2. how can i confirm the source /e/ is refercing firmwares

Some answers here: Sideload error Installing /e/ on LG V20 918 (Tmobile) - #3 by Tech-e1