To show how many people are watching and which countries they're in, your browser sends a heartbeat every 20 seconds with a random session id generated fresh on each page load. That id is not tied to any account or identity and is forgotten when you close the tab.
Your country is derived from your IP address using an embedded offline database (no third-party lookup). Only the resulting country code is stored - your IP address is not retained. Heartbeat rows are automatically deleted within about 10 minutes.
No accounts, no advertising, no third-party analytics or trackers, and no persistent cookies. That's it.