Is there a better reference device as the Polar H10 to study the accuracy of ECG and PPG heart rate monitors during rest and exercise?

A Polar H10 chest strap costs 90 USD, medical and research grade heart rate monitor devices cost between 1’165 USD and 47’500 USD: Is there no device among those expensive devices which beats the Polar H10 as far as accuracy is concerned? And has the Polar H10 really the “best heart rate”, as Rob ter …