First: nothing you buy will ever be free from exploitation under this system.

Ok but again, even if you think so, there are still different degrees of exploitation. Saying "nothing I buy will ever be free from exploitation" can also be used as an argument not to care about exploitation at all..

buying one product over another will make no difference in society and the world.

Of course it will.. You can argue that the difference it makes is so small that it is essentially 0, but it still makes a difference..

but they never manage to end the harmful production pattern that these companies were applying in the first place.

Just because you buying a more sustainably produced smartphone doesn't solve all the problems in the world doesn't mean that it has 0 impact..

In the end, conscious consumption only serves to feel good (falsely) about yourself.

No, it also demonstrates a way to improve something, even if that improvement is minuscule.. It also shows the potential issues and problems that come with it.. I would never claim that somebody buying a fairphone is changing the world, of course that would be ridiculous. Individual consumer choices indeed don't have a big impact on systemic issues.