BTW TBH I don’t really like Amazfit/Xiaomi, their terms tell you they can get basically all your data. With Pebble I felt a sort of trust, which I also have with Apple (but sleep tracking on a 1 day battery smart watch is bit of a bad joke).
I used the Bip U Pro on Android with GadgetBridge which is really amazing and perfectly privacy focused. Sadly when I switched to iOS I found nothing equivalent.
I want Pebble back.
Bip U has already just regular TFT display with poor battery life, maybe a better readability than OLED, but not comparable with transreflective displays and their battery life.
As you said you can use Gadgetbridge if you don't trust them, though I find GB experience very poor always losing connection compared to their own app, not sure if you can disable internet connection for the app to keep using it which would resolve privacy issues (I use also GBoard without internet access).
I use the open source Gadgetbridge app instead and it works well: https://gadgetbridge.org/
it's also very small, light and thin, pretty much impossible to find such compact watch since I don't want to carry bulky brick on my wrist (so no thanks expensive Garmin bricks with shorter battery life)
I'm now on my 2nd one, first I had brand new, it fell apart just before end of 2y warranty (basically the body inserted in frame without gluing, it felt outside, I could put it back and connect, just display colors were reversed but since it was in warranty I just used warranty to get money back, they improved gluing with newer versions), then went for OLED watch and gave up after maybe half year, gave new OLED watch which need to be charged at least twice a week to wife, it has unreadable AOD in sunlight (beause you need full brightness in sunlight or very least B&W AOD display instead other useless color combinations) and just bought second hand Bip for 20USD and I couldn't be happier, I'm thinking I could stock few of them into drawer in case something will happen to this one
plus for people with too much spare time Bip firmware is somewhat hackable with extended functionality