They could harbor microbial life, and perhaps more, in oceans (buried under a thick layer of ice) kept liquid by heat rising up from the planet’s core and tidal heating, if it has a companion. Europa may be just such a world and it’s right here in our own solar system. Of course, there isn’t any evidence that Europa has life on it, but it could conceivably be habitable for the right extremeophile. We can say that about very few bodies in the solar system.
If primitive life started and got a foothold on a world like Europa, surely we’d see spectra indicating possible waste release of oxygen or carbon dioxide. If Earth is any indication (and it’s all we’ve got by way of illustration), life will adapt and eventually fill every nook and cranny in an environment where it can be sustained.
Could be wrong but I’m of the opinion that life, particularly complex life, is extraordinarily rare even in a universe that is so mind numbingly vast from our perspective. Earth is a Garden of Eden racing through a cosmos almost unimaginably hostile to any form of life that might arise.