I'm curious about the size of the global Pascal programming community, at least in relative terms.
I don't know the answer...
Also, global may not give the full picture. There may be hotspots. Some countries with significantly higher activity, and others with very little.
There are (google it / search the forum) a couple of Website that "measure" the popularity of different programming languages. E.g. by counting how often they are (according to search engines) mentioned on websites.
And then keep in mind that sometimes it is split, sometimes "Delphi" is counted separately. That brings both numbers down.
You can on Sourceforge check the download statistics for FPC and Lazarus (mind that the latter contains fpc downloads, that would not be counted in the former).
To those numbers then add the unknown amount of downloads from mirrors, as well as directly from git, and installations for Linux via the distros' own repositories. (And if you wish, also add the cloned Codetyphon / unknown count).