For people in the future i solved this by making a new fragment to save the data in for all entities using a certain entityConfig and making it a SHARED fragment which apparently lets me set the data in it to be reused on all entities of a certain archetype:
UE_LOG(LogEntity, Log, TEXT("*** Building inventory template"));
FFPInventoryContainerConfigFragment config;
config.MaxWeight = MaxWeight;
config.MaxSlots = MaxSlots;
BuildContext.AddSharedFragment(FSharedStruct::Make(config));
BuildContext.AddFragment<FFPInventoryContainerFragment>();
BuildContext.AddFragment<FFPInventoryCommandQueueFragment>();
BuildContext.AddTag<FFPInventoryNeedsInitTag>();
UE_LOG(LogEntity, Log, TEXT("\t>Inventory template built [Config Fragment] -- Max Weight: %f -- Max Slots: %d"), config.MaxWeight, config.MaxSlots);