Pebble finish in paint

You could texturize the wall first. They make a spray on orange peel texture that might work

I agree on the idea of texturing the wall first. You can mix in texture with paint and roll than on but I've found spraying the texture on first, waiting for it to dry and then painting it will give a more even texture.

There is special silica sand that can be added to paint. Basically makes the paint slip resistant. Regular sand won't work.

Sand

The most common substance added to paints to create a textured final product is sand. Specifically, silica sand that is sold by home improvement and hardware stores for mixing with paint. You can add as much or as little sand to your paint as you like to create the perfect custom look and the paint should not be otherwise affected by the sand. It is generally advised to use silica sand rather than natural sand because silica sand is clean and consistent in texture.

Joint Compound

To create a look similar to Venetian plaster on your walls, you can mix a powdered joint compound into a latex paint. Once you have mixed the joint compound into the paint, you can create a plastered look on your walls by using the Milano plaster tool, a special texturing device that is commonly used for creating old-style appearances on walls.

Texture Additives

In addition to pure silica sand, most home improvement stores sell a variety of specifically designed texture additives to add into paints. Many of these products are sand-based, but may contain other ingredients and come in different grains so that you can create a fine, medium or coarse grain appearance on your walls.

here is more info

https://homeguides.sfgate.com/decorate-walls-pebbles-sand-64866.html

They do have rollers that will add texture to a wall. You might want to peek at them to see if there's one that you like, that will give you the effect without the need for a paint additive. Just a thought.

Henna

Hi! I would suggest spackle. You could create the texture you want and then paint over it. That would give you more control over the texture. Good luck!

Home Depot sells additives to add to paint

You could add baking soda to it to give it a thick texture