Answer: yes, it is only effective in solving minor problems.
Yes, there are commercially available anti-humidity paints. This is especially recommended for minor humidity concerns, such as condensation problems (in the kitchen or the bathroom). But this is not a quick fix, if your home is experiencing more serious problems (infiltration, capillary rise), the anti-humidity paint will not be of much help to you. You can apply this special paint on any type of support, both indoors and outdoors. It must be applied by brush or roller. It dries in two hours. In addition, it is washable and recoverable, so you will be able to put another paint or wallpaper on top. Regarding the price, it takes 20 to 25 euros per liter.