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Perhaps it can be called a rudimentary op amp. I can't say what is its overall performance.
The leftmost section is a differential amplifier.
The right half creates a simple output stage. The feedback loop consists of a series capacitor.
I imagine your question about biasing applies to the Nmos pair which I circled below? I find other schematics attaching additional circuitry to that bias wire. Right now it appears to have an undefined volt level.