Processes for using pyrolysis gas as a feedstock or a co-feedstock for making a variety of chemicals, for example, circular ethylene, circular ethylene polymers and copolymers, and other circular products. In these processes, pyrolysis reactor conditions can be selected to increase or optimized the production of pyrolysis gas over pyrolysis oil, and the pyrolysis gas which is usually used as fuel or flared can be fed downstream of the steam cracker furnace for economic use to form circular chemicals. Operating parameters of the pyrolysis unit may be adjusted to increase or decrease the proportion of pyrolysis gas relative to pyrolysis liquid as a function of their relative economic values.