Things that I did with my son and it’s working. My son is exactly the same except that he eats meat but doesn’t like fish. 1) put in single bites on the tray 2) try to eat what you are giving him and chew it with open mouth so he sees you are eating the same thing. 3) if you want him to try strawberry lets say, have a bite yourself and then offer him to taste your strawberry. This trick usually works when you are holding them close 4) don’t give him toast even if he doesn’t eat anything else! When they get hungry they eat properly. 5) I personally get help from my mom to feed him new things and he accepts it! That might work for you too if someone else feeds him! Don’t give up! You sometimes need to try things 10 times for them to accept the new flavour.
I would suggest asking for referral to a feeding specialist. Your public health may have connections but a doctor will have to do a referral. It can't hurt, but it might help. Sending hugs ❤️