What are normal readings?
A normal level of oxygen is usually 95% or higher. Some people with chronic lung disease or sleep apnea can have normal levels around 90%. The “SpO2” reading on a pulse oximeter shows the percentage of oxygen in someone’s blood.
If your home SpO2 reading is lower than 95%, call your health care provider.
More…
https://www.health.state.mn.us/diseases/coronavirus/pulseoximeter.html
The caveat is it depends where you live. At higher altitude a lower O2 sat is acceptable. Ask you doctor what the target saturation. is for your area