I’ve had no problems compressing Blu Ray MKVs into MP4s with handbrake (using MX Linux). My drive is a branded, internal one (I want to say LG or Asus.) I am at work right now, by I can look at the model number when I get home if you want. Interestingly, I have actually used it on both German Blu Rays and North American ones.
I’m in a very similar boat. I’ve been telling my husband gently that almost nobody in my family makes it to 70…