Dragon's Egg by Robert L. Forward is a science fiction novel about intelligent life that evolved on a neutron star.
Then there is The Black Cloud by Fred Hoyle, in which there is an intelligent cloud of interstellar gas.
It seems to me that life in an interstellar cloud would move at such a slow rate that we would not be able to detect it as life. I don’t see how there could be processes that acted on such a large-scale and on such a long-time scale that could be defined as life. The same considerations would apply to a galaxy.
The intelligent beings on the neutron star in Dragon’s Egg think a million times faster than humans. I am not sure that we would be able to interact with such beings, even if such beings were possible, which is more than a little unlikely.
It seems to me that some people have a prejudice towards thinking that the development of intelligent life is some sort of imperative for the cosmos. The cosmos does not favour intelligent life. There is no inevitably about the development of intelligence. The development of intelligence is an accident.
However, simple life, at the level of microbes, may be relatively common.
I think that we need to be able to define life. Is the Earth alive? The atmosphere and the oceans of the Earth, and some of its geological processes, interact with living organisms. That is an ecosystem, but overall I don’t think that we can say that the ecosystem is alive.
It is interesting that there would not be free oxygen in the atmosphere were it not for biological processes. If we detected a large proportion of oxygen in the atmosphere of a planet orbiting another star, then that would indicate that there was life there.