Can optical heart rate monitors replace ECG devices for certain applications?

A paper in PLOS ONE claimed, that the Polar OH1 can be used instead of an ECG device, as far as accuracy is concerned: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217288 A Swiss paper claims, that the Polar H10 chest strap is the Gold Standard for HR accuracy measurement: https://pubmed.ncbi.nlm.nih.gov/31004219/ The PLOS ONE paper gave us hope that ECG devices can …