I suffer from hypertension. I've had my diagnosis for about 5 years now. I was hopeful that the apple watch was going to be released with blood pressure support, but it didn't end up happening. Yesterday I saw an ad for Hilo (https://hilo.com/) and I pulled the trigger. It's not FOSS unfortunately, and the subscription seems a bit insane ($200/year), but my doctors are asking me for better data so that they can decide whether to change my meds. So I'll compromise my ethics a bit in the name of pragmatism.

I'm hoping that within the next few years, a locally hostable competitor will be created.