Between its speed of operation and https://www.sqlite.org/src/doc/begin-concurrent/doc/begin_co... I'm not sure when or even if this becomes a functional limitation.

In practice I don't think this actually matters.

SQLite can apply tens of thousands of small writes a second, so queueing them up works fine for all but the absolute largest scale applications.

This doesn’t meant what you think it does. They lock and take turns. You can have hundreds of clients (on the same machine), and it works fine.