Are you me 8 months ago? I was using Mi Band 8 while looking at maybe eventually buying a Garmin Instinct type watch. Then the Xiaomi died during a quick swim in the sea in early october and I pulled the trigger on the Instinct 2S solar.
The Garmin is great, it's so superior to the Xiaomi in literally everything that it's not even funny.
So you have a difficult choice, between European (Polar) at the cost of having to use their App, or Gadgetbridge, and then Garmin is really the best choice by far from almost any angle.