Much of the world’s medical equipment is made by a handful of monopolistic megacorps, but Milos Rasic built an open cardiography signal measuring device for his master’s thesis.
Using a Pi Pico W for the brains, Rasic’s device can record, store and analyze the data from an arm cuff, stethoscope, electrocardiograph (ECG), and pulse oximeter. This data can be used for monitoring blood pressure in patients and he has results from some of his experiments to determine the optimal algorithm for the task on the GitHub if you really want to get into the nitty gritty details.
See https://hackaday.com/2024/11/13/open-cardiography-signal-measuring-device