I wouldn't gamble with a watch for oxygen levels just yet. I got an Oximeter off of Amazon in the first months of the pandemic in case we got COVID and needed to monitor our oxygen. My spending account that comes with my insurance paid for it. I've also seen Equate from Wal-Mart make their own, although I can't provide a recommendation on that

https://www.amazon.com/dp/B07B9X3DBX/ref=cm_sw_r_apan_glt_fabc_VBT5JNB43MCZ87BB0SCW