Texture is not usually conducive to decals. So you can sand the texture down (not all that hard, but very, very dusty/messy) or paint them on. Of course texture presents a problem with crisp lines doing that also.
my grand-daughter put snow white & the 7 dwarfs on her daughters room walls , they look really good but her walls are flat (no texture) . I do not think the decals would stick to a textured wall because they need a flat surface to adphere to ...sorry . Maybe you could use really thin straight pins & tack them to the walls . I have used striaght pins to hold small picture frames to the wall & they work really well & do not leave large holes when you take them down. Unless you know where to look you can't see the holes at all.
We have a huge decal tree and birds and flowers in my daughter's room. They've been up almost a year with newly painted, textured walls, and the only ones that have come off are the ones her and her brother have taken off. I will say that it depends on whether they are good quality decals or not. We bought some really thin disney ones and they came up all the time. The Circo ones from target work great and are super cute. Congrats on your baby! Hope you have the nursery of your dreams. Good luck!
Maybe you could ask the seller of these decals on Ebay if they work on textured walls. I'm assuming it's just the "orange peel" texture, right? I would think they would stick fine. Especially if you use a paint with a bit of a sheen, like a semi-gloss under the decals.
Here's a site that says their vinyl decals apply to "lightly textured walls." They even offer to send a sample to try on your textured wall. And there is no shipping charge for a texture wall sample order. So you could try one out and find out if it works. The site even has some cute polka dots for nurseries.
@FoFa. Have u seen the cost of sponges these days. They have really gone up. the other day I couldn't find any decent size sponges for cleaning that weren't under $5 each. I use to be able to buy a 4-pack of good size sponges for $2.50