Ds1 only drinks milk and water so thats not been an issue for us, thankfully. Well done on the no squash! You can dilute fresh juice btw. We did switch to semi skimmed on the advice in Brain Food Plan.
Ds1 used to have crisps every day in his packed lunch...hasnt had any since end of Dec and has never even mentioned it!
I now use Doves farm organic gluten free pasta and neither ds1 nor dh have noticed! Its very nice (and I am very fussy)
We have rice once a week usually and ds1 also likes unsalted rice cakes as a snack too which are very healthy.
For snacks/treats he has homemade flapjacks (I can give you the recipe if you want) and homemade oaty cookies. I like to make them myself as a) all ingredients are organic (or mostly anyway) and b) no additives, E numbers etc.
He also likes tomato soup and he has ketchup with meals too. I dont think it helps to be too prescriptive straight away and you can always buy the organic low salt and sugar version which we use (heinz).
Ds1's big treat/fave is pizza (cheese and tomato) and I do let him have 2 x per week which theoretically I shouldnt but hey, he is doing so well and life would be pretty boring without treats!
Wrt fruit we do struggle with ds1. Veg is ok...frozen peas and sweetcorn. Fruit has always been an issue tbh so he has a carton of organix fruit puree each day...is not ideal obv but better than nothing.
All in all its not been too hard diet wise for us...ds1 has never liked sweets or choc - his big issue was too many carbs - a common issue for kids with develeopmental delay syndrome.
Good luck
PS: Wrt supplements: we use Floradix kindervital, saludynam and chewable vegepa from amazon.