It's an extremely popular engine for visual novels, to the point where it's fairly safe to assume any given VN is made using Ren'Py. For example, last year's Slay The Princess.
Needy Streamer Overload was the big visual novel of 2024 I think, which was Unity.
The most popular modern-ish visual novels I know of, like Fate Grand Order, Dangenronpa, and Ace Attorney, aren't Ren'py.
I feel like Ren'py is in the minority for modern popular visual novels, and it's definitely in the minority if you include re-releases of older visual novels.
I'd expect it to be in the vast majority for independent visual novels.
