I had an Amazfit BIP for a while that had a color e-paper display with a battery that lasted over 30 days. I think they have since gone OLED but one cool thing about it was, while they had their own app with a login, I could alternatively sync it directly with a third party app on Android that was called “Notify And Fitness”. I only mention it because within this particular app the info never left the device. Perhaps there is something similar today, but I have since just given in and gone Garmin.