I've been using a Powerbreathe for inspiratory muscle training. The daily exercise only takes a few minutes. But it requires occasional cleaning, and the spring valve sometimes gets stuck closed. I haven't noticed any obvious decrease in blood pressure.
There are inhalation resistance trainers on Amazon for as little as $20. I'm doubtful the more expensive devices offer any benefits. In fact the simpler less expensive models look much easier to take apart and clean. As long as you are breathing against resistance, you're getting a benefit.
https://www.powerbreathe.com/product-category/breathing-trai...