I've got the Aktiia/Hilo band and I'd recommend it if you're wanting to keep vague[0] track of your 24/7[0] blood pressure. Needs calibrating every couple of weeks against the band but that's not an onerous procedure[1][2].

(Probably worth getting a cheapo monitor as a secondary check though - I've got a Renpho bluetooth one.)

[0] It only really takes measurements when you're not "moving" and that can be "running around", "jumping up and down", "typing furiously", etc. which does lead to gaps and only 3-4 measurements every 2 hour slot. Also their app is a bit rubbish and they don't have a decent export story - if you want more than their "daily average → Health", you need BPExtract to OCR the monthly PDF reports (which you have to request by hand, BTW!)

[1] Protip! DO NOT drop the band onto its on/off switch because it's fragile and will BORKEN itself. Mine got stuck in the on position but I've subverted the problem by sticking a magnetic MicroUSB end into the charging point[3] - applying power kicks it into charging mode and removing it leaves it in "ready to use" mode for 5-10 minutes which is more than enough for standard calibrations and testing.

[2] Although their new "BP via the camera and finger" doesn't work AT ALL for me. Almost never gets a reading.

[3] Which I've started doing for all MicroUSB devices because I've somehow managed to snap off 3 MicroUSB ports internally. Shoddy workmanship.