Flutter Looking for a package for nested relational Maps/Lists code generation

Question

I have 3 nested DropDownButtons, Category, SubCategory and Products.
Each item in Category Map has its corresponding SubCategory Map.
Each item in SubCategory Map has its corresponding Product Map.
All the relational linking is done in an interface(?) , consisting of simple switch statements, exposing methods fed to the DropDownButtons. The code works as intended.
My problem is that maintaining, at a production level, all these maps and relations is gonna be a headache and highly prone to mistakes. Especially if they are expanded, they most surely will.

So Im looking for a package to either properly maintain the nested Maps part , or the relational part, or both! Through code generation, code styling, anything.

Any lead appreciated, thank you in advance.