If your whatever device doesn't support a root CA from 2016, chances you should not let it connect to anything over the internet. Most bad software comes from "hardware" vendors, who think they can handle them the same as any other physical part. Stop blaming software people.

But usually these other devices can also update their software, it is quite unique for the android operating system to run old and unupdatable software.

Or they should if they are web facing. For security reasons at least.