Maybe you can take a look into "Applied Energistics 2" from Minecraft.
Its a storage mod similar to yours and maybe you can make a sort of storage cell to store the items on and that you can select a specific item that can be stored on it. When the storage cell is full it wont pull more items into it till you make a larger storage cell.
If you need more information I can also assist you in more details how the mod in Minecraft works or you look on Youtube there are plenty of videos explaining the mod.

good afternoon, I am very familiar with this mod, initially it was planned to have similar cells and computational units to scale the coverage of processed machines, but until I figured out how to do it correctly, I’m just starting to make mods for factorio

in theory, you can even build production based on orders, since factorio can change the recipe according to the script