It's good you're considering integrations. For any app linking Bitcoin and Nostr, the primary concern should always be preserving genuine decentralization and your self-custody of funds.

For sure. So far it has NIP-46 implemented. So you can sing in with something like nsec.app. You can share any workouts logged in Kauntor as a Nostr note. If the shared workout has heart rate data, then the Kauntor Nostr account automatically sends a Zap for each minute spent above heart rate 100 bpm. See #SweatForSats for examples. I use a start9 self hosted Alby Hub for sending these zap rewards