Earth-like biospheres on other planets may be rare

This is interesting but is there a set composition for a suitable planet as in is there a minimum to maximum range of say Oxygen or Nitrogen to make life more likely

This is a slightly related resource looking at the composition of atmospheres in our solar system.

On a positive note there is a catalogue in development of potentially Earth like planets.

The James Webb telescope will advance our knowledge much further.

https://www.jwst.nasa.gov/