Honestly, after seeing that there’s truly no GOG equivalent for movies, neither now nor probably ever, this is the solution I like the most.
If I want something fast, I get the file through “other means”. If I like it and want to support the production behind it, I add it to a list and at the end of the year I do what you’ve said.
This way I neither accumulate DVDs nor throw them in the trash, I support the production, I make my neighbors happy and get a high quality file on top. Sometimes it’s the simplest things, thanks for the reminder and the idea :) Hopefully in the future this will all be possible digitally.