WPT details: WPT tests covers failure cases (e.g. when the handwriting recognizer isn't supported). The success cases requires platform and operating system integration, and can't be tested solely in WPT.
An API for web applications to make use of advanced handwriting recognition services (e.g. those on operating systems) to recognize text from handwriting drawings (inks) in real time. In this context, handwriting drawing means the temporal and positional information used to describe a human handwriting process.
This is needed to make use of the latest advanced proprietary handwriting recognition algorithms, reduce the need for third-party integration. This API makes it easier to develop web applications that process handwriting inputs (e.g. note taking app).
Docs: https://github.com/WICG/handwriting-recognition/blob/main/explainer.md
Explainers: https://github.com/WICG/handwriting-recognition/blob/main/explainer.md