I was going to suggest the Pinetime, but it is far from close to what you're asking. Have you looked at the Bangle.js 2 watch? It has GPS at least.
Have checked PineTime, and seriously considered it. But as you said, and I remember, it fell short on features. Will check Bangle.js!
Just adding a link: https://banglejs.com/
Looks nice!
You can install new apps from the web or develop your own using JavaScript. All you need is a Web Browser (Chrome, Edge or Opera) and you can upload apps or write code to run on your watch wirelessly!
However, I find it strange that they only advertise proprietary browsers and no open-source alternatives.
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
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