Why does it even need to be forked? The whole point of using SQLite as a foundation for distributed, edge, or other stuff is that it's a solid foundation that can be trusted to not change too much.
Why the need to open SQLite to contributions? Build your fancy distributed, or edge database on top of SQLite and you won't need to modify SQLite at all.
Just to clarify: sqlite3 changes almost literally every day[^1]. However, the project has always placed a premium on backwards compatibility and the developers go way out of their way not to break in-the-wild applications. Given how many databases there are ("billions and billions"), even the slightest backwards incompatibility is likely to affect _someone_, and even 1% of "billions and billions" is a significant number of databases.