Couch distance and especially screen size can vary a lot. I can clearly see the difference between full HD and whatever resolution DVDs have at the 2~3 meter distance at my parents’. (43" full HD screen). Same goes for 4K vs full HD on my 60" screen.

In any case, my main point was that DVDs are no viable alternative to streaming services since all of them offer much better quality. If you really want to replace streaming services at similar or better quality, go for Blu rays.

DVDs have atrocious quality. Blu rays are where it’s at

Well they published their source code.

It’s not as permissively licensed as usual open source projects, but I would argue that in the true sense of the phrase, this falls under “open source”.