Recently have been really impressed with the Amazon prime app. Also Fandango has a handful of 3D movies you can download or stream in 3D. I was surprised how well it streamed.
I don't mind encoding them down which takes about 30 min. on my old PC. I like MKV format resulting in about a 4.5 GB file for each movie. Then I rarely use the BR disk again.
A program I've been using for decades, is stereoscopic player. With that player you can pretty much do anything regarding 3D. You can convert old interlaced and Sensio 3D movies to SBS for 3D viewing on the Quest. There is a free trial. Not sure of the price now, I bought my license in the Win 98 days. I also use it to play or stream my HD SBS from BR and I find the image quality to be the best for 3D movies.