[mosselman]

So this is totally off-topic and a bit you are going to think I am very rude for intruding:

I was just looking around whether it is possible to create custom apps (on phones) to sync with smart watches (generic ones from places like aliexpress). I have no experience with bluetooth, but is there anything that would prevent you from making something like that? Even if it is just for myself, I don't need to release or anything.

Do you happen to know if it is possible and where I can look?

[nickff]

There are no hardware obstacles to doing that, and BLE (BT4 and 5) support custom protocols. That said, I think you will find that working with the proprietary operating systems and architectures on watches and phones is much more difficult than you anticipate.

[mosselman]

I figured it is most likely too difficult. For the amount of work it would take I could just buy an Apple watch and be done with the privacy concerns I have with cheaper trackers, but once the seed of an idea is planted it starts having a life of its own.

I think this is an idea I shouldn't water though ;).

[naraic0o]

try gadgetbridge, it's an OSS project that already does this for cheap fitness trackers and some watches.

https://gadgetbridge.org/

[mosselman]

Wow this is amazing! It is exactly what I was looking for except for it being on Android only, but at least I now have a whole code base to learn from. Thanks!