Where can we find validation papers for consumer grade optical heart rate monitors?

Last Updated on December 12, 2023 by pg@petergamma.org

Here is one for the Apple watch 1:

https://journals.lww.com/acsm-msse/Fulltext/2017/08000/Variable_Accuracy_of_Wearable_Heart_Rate_Monitors.22.aspx

Here is a paper for the Apple watch 3:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6732081/

Here is a paper for the Polar OH1:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217288

But we do not know of sellers of devices who sell products for scientific studies who picked those up in their store. Furthermore all of these devices have already successors and we do not know if they are still available from the manufacturer.

And we are asking the question: are these devices which are interesting for scientific studies? If they where:

a) would not the sellers of these devices still offer those?
b) would not validation papers appear for latest devices which are on the market?