Artificial livers won't come at once
The liver is one of those things that gives you a false illusion of being "one thing." Indeed, it's a plate sized object that is an amalgamation of hundreds of chemical factories. It literally has a subset of ~500 chemical processes running at any given time [1][2]. But to group them into major categories, we'd describe it as an organ that:
Makes things: Cholesterol, hormones, proteins, bile, clotting factors.
Detoxifies and filters: Breaks down drugs, alcohol, toxins. Filters and breaks down old/damaged red blood cells, recycling iron and converting heme into bilirubin.
Metabolizes: Carbs, proteins, lipids.
Stores things: Glycogen, vitamins (A, D, E, K, B12), and minerals (iron as ferritin, copper). Also acts as a blood reservoir, capable of holding a significant volume of blood and releasing it during hemorrhage or shock.
Goes without saying that no human engineer is going to release a product with 500+ specs all operating with zero bugs. Rather, release will most likely happen slowly, following a process similar to the one below:
- Macro machines performing some liver functions. Already happening. See [3].
- Implantable devices with inbuilt accessories (most likely nanomachinery) performing a select few operations to mimic normal liver function.
- Incremental releases, each doing an even better job and performing more functions.