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/