Two tidbits from me:

Several years ago, I got an omron wrist cuff blood pressure monitor. Some doctors showed heavy skepticism at the time but I've never seen any reason to think it's inaccurate when properly mounted and with healthy batteries.

I had a sleep study done last year using a brand new machine the lab got (literally unboxed while I was there) that uses a combination of the ecg signals and pulse timing to calculate blood pressure continuously once calibrated. Seemed pretty cool to me and I got the impression this technique is fairly new?