The scientific definition of a berry is a fleshy fruit that came from a single ovary in the flower. Thats it. I don’t even know why they used the name berry on this term because it makes no sense and I tell you this as someone studying botany. Like none of the nuts you know are true nuts either. If a nuts shell opens on its own it’s not a nut so peanuts, walnuts and almonds are not nuts because if you plant these in fresh soil they will sprout and the shell opens. However if you plant a fresh hazelnut the shell stays on while the plant germinates from the seed, hence it’s a true nut. So stupid I know. This has use in botany but these botanical definitions have no use for normal people. That’s why we talk about “botanical definitions” and “culinary definitions”. In the common culinary definition a berry is a small freshy fruit which is the definition you know.
Bonus: in botany everything from a flower is a fruit. That means wheat is a fruit, rice is a fruit, beans are fruits, peas are fruits, all nuts are fruits, every seed is a fruit, a pine cone is a fruit, and it just goes on. But no one in their right mind would make a fruit asket with pine cones right? The botanical definition is useless outside the field of botany.
It appears you are right. Conifers and other gymnosperms are totally outside the definition of fruit and cannot have fruit by definition. The seed cone is however an analog of a fruit for the gymnosperms. It doesn’t have to do with petals however. Lots of flowering plants don’t have petals. Example are these wheat flowers. You have to cut up the plant to even see the flower.