Question, does having it in pure rust, opens possibility of embedding pgrust directly into binary, making it an alternative to SQLite/turso?

It absolutely can be embedded. The bigger enabler is replacing the process-per-connection model with a thread-per-connection model. Projects like pglite[0] had to give up concurrency because of it. We also support compiling to wasm so you can embed it in the browser too, which is what powers pgrust.com

[0] https://github.com/electric-sql/pglite

[1] https://pgrust.com/

I'd help with testing if you helped them add this. I'd be interested in this.

Look into tursodb for this.