I have an OWC external Blu-ray drive and they’re not that expensive and it reads and writes and also will do DVDs and CDs and it’s way faster than the external Apple drive, which I don’t even think we’ll do Blu-ray
The 3 TB figure is for Blu-ray discs, but typically low one gigabyte for a lot of of them
The only other thing is, it’s hard to then also get all the little extras like deleted scenes and trailers and stuff. I strictly just do the movie.