I did an 870 years ago when those kits first came out. Looked ok when it was first done. Edges peeled up and it wore and faded. I cleaned it all off and found that water had crept into the creases and overlaps. No lasting damage, but would have if I didn’t peel it. Don’t waste your money is my advice.
If you really want it camo, the dip kits from “my dip kit” are actually pretty straightforward and fun. I’ve done a couple with one kit. Don’t expect perfection but, if you follow the instructions, you will likely be pretty satisfied.
There are professionals who do it as well.