Texture can play a part in what a fussy eater will or won’t eat. Each fussy eater may have different textures of food that they dislike. For some it may be slimy. Others may not like crunchy. Maybe creamy foods creep them out. It could even be a combination of textures they have a problem with. Try to think of all the foods they dislike and see if there is a common texture among them. Then try to devise a way to change or mask it.
I have a little bit of a problem with crunchy vegetables. That made broccoli a little hard to deal with. What I’ve found is that if I cut it up small enough and mix it with something else like rice, then I am able to deal with it better.
I also have a problem with slimy foods which I suspect it my issue with a lot of fruit. I haven’t come up with a way to deal with that yet, but I’m open to suggestions.