It’s not clear what UI Fast Pair on Wear OS will take, while Google has not explicitly announced the availability of Fast Pair on Wear OS.
The closest was at CES 2022 in January when Google described “audio connectivity with wearables” as an existing Fast Pair functionality:.
Meanwhile, it’s possible that Fast Pair on Wear OS is meant for the Pixel Watch.However, the Pixel Watch page describes Fast Pair’s discovery and connectivity features mentioned by Play services today. In theory, Fast Pair should not be limited to the Pixel Watch and something all Wear OS devices benefit from whenever it launches