Basically your only other option is to find the keys for each BluRay you own yourself. I did go through the hoops a while ago and wrote it up: www.bennee.com/…/playing-blu-ray-under-linux/#pla…
However it’s a pain sourcing the encryption keys you need for each disk. While I work hard to prefer FLOSS apps over their propriety equivalents in this case I’m happy to pay the small fee for a perpetual licence of MakeMKV.