Welcome to the Community @Waldorf
Many of us on the Community have our opinions and mine is similar to yours. Since your question was about testing I’ll tap @DenisGallagher or @BrendanMays to respond.
My personal suspicion is the tests focus on outcomes (eg what one sees and hears and experiences), not what is behind the curtains. What is behind the curtains certainly affects apps long term, manufacturer dependent, but as hardware ages even any particular AndroidTV will meet an end date. Will that be longer or shorter than a manufacturer that continues to roll their own? It is not only OS but also processor, memory, and support for specific chipsets. An allied topic, and there are others on the Community re Smart TV issues.
My belief is those TVs still using proprietary OSes will eventually have to succumb as a matter of economics in the same way computers, network devices, and electronic products of all types have adopted linux/open source in some manner. ‘Resistance is futile, we will assimilate you’ might be the case, given enough time regardless of what might be better or worse, all because of the economics of building and then maintaining something special.
