Is a mosfet considered as a transconductance amplifer?
A transconductance amplifier generates a current depending on an input voltage. A MOSFET in common-source configuration would show the behavior of a transconductance amplifier, a MOSFET in a source-follower configuration however would behave as a voltage source.

The MOSFET itself is usually modelled as a transconductance, but it does not constitute a whole amplifier. Nevertheless sometimes an "intrinsic gain" is attributed to a MOSFET to specify the gain that could be achieved if it was biased using an ideal current source. For this hypothetical application, the transistor is regarded as an amplifier.