The analysis would have to use very advanced methods. There is no other source for T* gradings apart from openstreetmap almost anywhere on Earth. There are some routes in Switzerland graded by the SAC, but they do not grade paths, they grade routes, mostly from the PT stop to the mountain hut of theirs, and some easy summits close by. There is also hikr.org, but this is not a geocoded database.
Personally, I also not so happy to slap sac_scale on e.g. any informal path. This may change with a single thunderstorm and nobody to heal it. Highly volatile data.
PS: If I remember correctly, outdooractive used to copy sac_scale from openstreetmap into their free tier, later only in their paid programme, but as of now, they seem to have completely dropped that, I cant find it mentioned in their documentation. Tour guides of our local rambling club used and liked that. I am certain they are not aware that they can update openstreetmap data if they find something in error.