Closest thing right now: a cheap Colmi R02 ring (~$20) paired with Gadgetbridge, the open source Android companion app. The firmware on the ring is still closed, but Gadgetbridge pairs it without the vendor app or any account, and the data stays on your phone. It syncs heart rate, SpO2, sleep, steps and stress, and the R03/R06 work too (HRV on newer firmware).
Check before you buy: some rings sold under the same model names use different hardware that Gadgetbridge can't talk to. Support list: gadgetbridge.org/gadgets/rings/
On blood pressure: no ring measures it properly. Without a cuff it's an estimate from pulse data, so treat any BP number from a ring as a rough trend at best. For real readings, a cheap upper-arm cuff is better.
If you'd go fully open source and accept a wrist device, look at the Bangle.js 2 or PineTime. Both are lighter than most smartwatches, though still not a ring.
quillfox / quillfox 🦊
npub1f3…fd45d
2026-10-14 12:00:45 UTC
in reply to nevent1q…lqp3
Author Public Key
npub1f3253es62wcrt6cgfqcj53qh6jwzt94l4v9u86mp7hnwel84uhzqvfd45dPublished at
2026-10-14 12:00:45 UTCEvent JSON
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"content": "Closest thing right now: a cheap Colmi R02 ring (~$20) paired with Gadgetbridge, the open source Android companion app. The firmware on the ring is still closed, but Gadgetbridge pairs it without the vendor app or any account, and the data stays on your phone. It syncs heart rate, SpO2, sleep, steps and stress, and the R03/R06 work too (HRV on newer firmware).\n\nCheck before you buy: some rings sold under the same model names use different hardware that Gadgetbridge can't talk to. Support list: gadgetbridge.org/gadgets/rings/\n\nOn blood pressure: no ring measures it properly. Without a cuff it's an estimate from pulse data, so treat any BP number from a ring as a rough trend at best. For real readings, a cheap upper-arm cuff is better.\n\nIf you'd go fully open source and accept a wrist device, look at the Bangle.js 2 or PineTime. Both are lighter than most smartwatches, though still not a ring.",
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