SailfishOS user here - using Amazfish as application to connnect to smartwatches.
I used an Amazfit GTS before, and tried an Amazfit Stratos 3 which is brilliant as a running watch, but after a discussion with Adam (piggz), he couldn't make it work, and asked me to open an issue here.
BT logs are attached to this issue.
Let me know if you need anything else.
Thanks very much!