After Google has taken over Fitbit, there are already some indications of changes, but for now things are still going according to plan. The Charge 4 replaces the Charge 3 predecessor. While the monochrome display remained, GPS and the SpO2 measurements are new. In the meantime, Huawei has also enabled the latter in the Band 4 Pro, which is significantly more affordable in comparison. Is the additional cost of the Charge 4 worth it?
https://www.notebookcheck.net/Fitbit-Charge-4-Fitness-Tracker-Review-Twice-as-expensive-as-the-Huawei-Band-4-Pro-and-also-twice-as-good.470786.0.html