And how much of a pain in the ass is it to buy DVD box sets and rip them? Presumably that’s legal for personal use? Is that the only way? :(
It can be a pain at first when you figure out a schema, look for software etc., then just a matter of inserting a disc and pressing a button. DVDs are easy to rip, there are fully open source programs to do it, for example libcss from VLC team. And DVDs don’t require using leaked decryption keys like BluRays.
It is legal depending on the country. In US it’s in gray area as you strip down DRM. In country I live in (Poland) from my research there are no such measures and copyright works differently. In Poland the movie/music is untied from medium you bought it on, so copying is legal but selling or giving those copies without destroying other copies you have is illegal.
My advice is that for first dozens of movies don’t play with Jellyfin and storing them. DVD player on USB is the best and rip just to have movies for a trip or on a phone. Just out of simplicity, why spend time managing backups, storage shares and additional machines when there is only a few titles to manage.