I wrote pyinfra so am biased but we used it at my previous company on a fleet of roughly 1.5k physical boxes (including deploys spanning all of them at once) extensively, so it scales to that level well. We had probably 30 groups within that each with their own deployments as well and all tied together using a single Jenkins box.

I would love to test beyond that but haven’t had the opportunity sadly! Performance and scale is a headline feature so will always look to push this further.

There was more commentary about it when it was posted in 2020: https://news.ycombinator.com/item?id=23487178 (although I didn't go through them all looking for endorsements)