Weaning pouches taste of ... well weaning pouches. The weird combination of ingredients (such as spinach and blueberries) with a high prevalence of sweet tasting food such as sweet corn and carrot combined with the high temperature and pressure process has develop a preference for taste that doesn't exist in real life but he will like similarly sweet tasting food .
The first step is to have him seated. The only place one eats is at the table. Not walking around, not on the sofa, bedroom, car, street, .... name it . This is the rule for the whole family, parents included,
The second step is when seating is consolidated to empty the content of thew pouch in the bowl. Only babies suck on food. Chances are the vomit-looking content might put him off. If this doesn't work, add a bit of vinegar to the pouch before giving it to him and when he says "beurck" it tastes bad, look at the ingredients and say "oh, they changed the recipe, sorry honey, let me make you some nice pasta"
If you want to change his eating habits and preferences, you need to remove the competition, so as long as there will be sweet stuff (not talking real fresh food such as fruit) you stand no chance.
Stop buying new pouches. Let the one you have go "bad" and enforce the "at the table " rule .
The more you wait @15PD18 , the worst it will be