Debian is huge - that's why so many other distros use it as a base!

So, yes, all those packages are maintained either by an individual Debian Developer or a team of them.

There are third party repos, but they're (currently) neither as widespread nor as commonly-used as those for other major distros. This vote won't affect them, and you might potentially expect to see their use grow if one of the harsher options in this GR were to pass.