Web Bluetooth does not exist in Safari. On a Mac that leaves two ways to connect a smart trainer — use Chrome, or use this app. Everything else is identical: the app opens the same Pixel Watts you are looking at now, so it updates itself and never needs reinstalling for new features.

Looking for the current build…

After downloading

Open the .dmg, drag Pixel Watts into Applications, and start it from there. On the first ride macOS asks once for Bluetooth — that prompt is the trainer connection, and pairing will not work until you allow it.