Yep! No fresh food until 6 months.
You can make treats though!
Try this one:
1/2 cup rolled oats
1/2 cup ground pellets
1/4 (-+)cup water
Bake them at 350°F for 10-12 minutes.
My girl loves them!

I would stay away from oats. You want to keep only the food that is currently ate in his diet for his treats. You can still soak the pellets and squish them and then bake them but don’t add anything extra. It can upset his gi tract and lead to diarrhea which can be deadly for babies.

Leafy greens you can start at 3 months, and fruit and sugary veg at 6 months. I agree with BH, stay away from oats if your bun isn’t used to it. My boys loved oats at that age (and still do!) but their breeder fed it to them, so I would give about a teaspoon every few days as a treat. Because he’s 3 months old you can start giving him fresh greens. Start out with mint or parsley and give 1-2 leaves and just monitor his poop. Then you can start introducing other fresh greens. Start with romaine and butter lettuce as these are easiest on their tums.