VLC has over 6 billion downloads, obviously there are people who downloaded it multiple times, but that's getting close to averaging one per person in existence.
6 billion download announcement (eventually leads to X/twitter): https://techcrunch.com/2025/01/09/vlc-tops-6-billion-downloads-previews-ai-generated-subtitles/#%3A%7E%3Atext=VLC+media+player%2C+the+popular%2Can+AI-powered+subtitle+system.
Not directly comparable, but guesses at the number of Linux servers out there are in the 10s-100s of millions.
They didn't go into depth at all, don't believe we even have one with a name, but they talked about seeing federation ships made entirely of 'holographic containment walls' in Discovery Season 3. Pretty sure it was when they first arrived at federation headquarters in the future.
There was also that ship in insurrection where it was just one giant holodeck, but still existing inside a regular ship. The concept just hasn't made it into something that's broadly popular in the mainstream trek fandom.