Not paint-by-number, but a similar concept: use stickers to create fun images with a 3D effect, including mockups of famous artworks
Sticker Books for Kids 2-4, (600+ Stickers & 13 Scenes & 14 Coloring Pages), Animal Habitats Stickers Coloring Book, Activity Book, Travel Sticker Books for Boys & Girls
Paint By Sticker Brand Page
Bluey Color & Sticker Activity Book, Crayola.com
2 Pack Sticker Books for Kids Ages 4-8, Crafts for Kids Ages 4-8 Sticker Paint Books Boys and Girls Birthday Gifts Party Favor, Travel Activity Book Set for Learning (Princess+Mermaid)
Holiday Gift Guide: Kids/Teens/Him/Her - Mel's Kitchen Cafe
2 Pack Sticker Books for Kids Ages 4-8, Crafts for Kids Ages 4-8 Sticker Paint Books Boys and Girls Birthday Gifts Halloween Party Favor, Travel Activity Book Set for Learning (Animal+Insect)
Shop Sticker Books - Planner, Words, Love Stickers & More
Let's Look: STOCKING STUFFERS - Mix & Match Mama
Crayola My Little Pony Color and Sticker Book
2 Pack Sticker Books for Kids Ages 4-8, Crafts for Kids Ages 4-8 Sticker Paint Books Boys and Girls Birthday Gifts Halloween Party Favor, Travel Activity Book Set for Learning (Animal+Insect)
Workman Publishing Paint by Sticker Books