Adding a Fleet Carrier module which over time will convert 1t of Indium and 1t of Aluminium stored in the cargo hold to 2t of Domestic Appliances, and keep working through this conversion so long as it's stocked up, doesn't seem that difficult and Frontier could probably put that module together (with a bunch of different cargo chain options) pretty quickly if they wanted to.
There are two big problems with that module, though:
1) 1t Indium + 1t Aluminium is considerably more expensive than 2t Domestic Appliances. It'd need to make something like 20t for it to be worth it. All the arbitrariness of the market prices (every single refined metal is a lot cheaper than the same mass of its ore, most manufactured goods are cheaper than the same mass of even cheap refined metal, etc) would need to be fixed to make most production chains make a profit while keeping to conservation of mass, and that would shake up a lot of the trade economy. The way that BGS states affect trade prices would need to be substantially toned down, too. Lots of things in the trade sim which are currently fine because the NPC factions don't have a budget and don't need to be profitable would need a complete overhaul to be player-usable. [1]
2) What are you going to do with 1000t of Domestic Appliances once you have them? Even with the FC module instantly converting all its raw material supply and not having any separate maintenance costs, the only thing you can do with them is sell them to a station, and you'd likely have been more efficient just buying them from an Industrial station in the first place. The same applies to essentially every commodity. So it needs not only uses beyond "sell them" adding for at least the end-of-chain commodities, but also extreme adjustments to the NPC markets so that they don't provide enough of those commodities on their own. That's again a much bigger change in terms of either the BGS or direct player use of a whole lot of cargo.
The one case it could potentially work right now is a production chain leading to Tritium, where the NPC markets are insufficient to meet demand once you get a few thousand LY from the bubble, and there's a player demand in the absence of NPC markets. But then Tritium is directly minable, so you'd either need to be able to run the whole production chain from mined materials where 100t of precursors is substantially quicker to mine than 100t of Tritium (or the exchange rates break conservation of mass, of course, so you only need 20t of precursors to get 100t of Tritium), or you'd need a way to transport other precursor commodities to the deep-space factory from the bubble which could be used to just transport Tritium directly instead.
(And that's with all the existing deep-space player-run Tritium depots essentially being run as a non-profit service: they'll cover their costs and make a nominal surplus but it's definitely not a fast way to make money)
I'm not saying it couldn't be done, but the precursor steps of sorting out the entire commodity pricing structure to have something approaching a rational profit-making balance at all points (which would need careful alignment to things like bounties and exploration data which don't have the same considerations) would be immense and should absolutely be done first because if the economy can't even be balanced with purely NPC production it's certainly not going to be balanced once players get involved.
[1] This gets even worse if the production chains can make ship/outfitting modules, which are player-usable, because then comedy points like "the Sidewinder hull costs considerably less than its mass in scrap metal" suddenly become gameplay-relevant rather than minor sources of fun, and all those prices need rebalancing too.
