Son refuses to eat, any tips or tricks?

My son is 16 months old and refuses to eat ANYTHING. Like it doesn’t matter the texture, taste, NOTHING. He will only eat puréed baby foods in a bottle with a scoop or two of formula. I’ve spoken to his doctor about this at his 15 month appointment as well as his 6th and 12th month appointments and I do have an appointment scheduled with a feeding and swallowing specialist for April 2nd, which was soonest I could get him in. He was born prematurely at 31 weeks, not sure if that has anything to do with it. The doctor said he’s still growing on pace so it’s okay to continue what I’m doing to feed him as he’s not malnourished or anything, but do you guys know anything I can try to entice him to eat, or any foods your toddlers enjoyed? My first born ate everything in sight so this is new to me and frustrating because I KNOW he needs more than formula and purées to sustain him at this point and I feel bad for not knowing what to do.