I really need to automate this somehow, but my latest estimate is 3.13 million active users of Flathub!
This is a number of updates delivered to a popular dependency, org.freedesktop.Platform.GL.default//23.08, between the 23.08.14 and 23.08.15 releases. This was less than a month window (March 18 through April 9).
Pretty impressive stuff!
Edit: updated, more realistic stats based on @alatiera; thanks!
