Smartwatch: Garmin (Fenix 6 gen and above if you want sleep monitoring) with gadgetbridge on android (preferably GrapheneOS) and selfhosted Endurain. Seeing as this is c/Selfhosted you can also roll your own dashboards with Grafana.

You’re thinking Garmin, really? Privacy? Actually Garmin’s T&Cs are IMO the best of the big names privacy wise, especially if you’re in the EU, but they’re publicly traded and subject to the ‘I have altered the deal, pray I don’t alter it any further’ changing terms at their whim, or just getting bought out and drained dry.

You know what’s better than OK T&Cs? Not giving them any data at all. On gOS I can pull the network permissions for Garmin Connect and still use it to set up the watch, do custom activities and so forth. When finished disable it and enable GadgetBridge. If you want watch faces do that with Connect IQ and then uninstall.

There are other gadgetbridge compatible devices but none with the build quality, feature set and quality health data. It’s been running for GB for more than a year and they haven’t sicced their lawyers on it.

You can also just connect it via USB and use any software that handles GPX etc. files.