The new specs were found in the updated material for manufacturers in the MFi program, according to sources. Apple does offer a fast 29W USB-C Power Adapter that will load your iPhone to 50% in 30 minutes flat, but that one will cost you $49 extra. Therefore, third-party manufactures using MFi logos without official authorization from Apple will face great legal risks. This means that accessories no longer had to include a cable with products and bring down costs as users could use the Lightning cable they got with their iPhone for charging the accessory as well. Now third-party companies building things like controllers, battery packs, and speakers can use USB-C charging while still keeping Apple's stamp of approval.
As is often the case with Apple, there are still unfortunate limitations: USB-C ports can't be used for pass-through charging or syncing iPhones or iPads; so don't expect a USB-C charging case to come to one of Apple's devices in the future. Products are also allowed to bundle USB-C cables with the MFi accessories.
This is a helpful move for users as more tech companies are beginning to use USB-C ports on their products. That is one of the reasons Apple has added specs for other non proprietary connectors in the past such as the Ultra Accessory Connector for headphone makers a year ago. They can also use the USB port on their Mac with the same cable to charge their Apple device.
As for the Lightning to standard audio jack cable, it will save you having to plug in the extra adapter that Apple includes in the iPhones' boxes ever since it ditched the jack, and plug a Lightning cable from the iPhone directly in whatever audio gear you have that demands a 3.5mm input. The new cable, however, would allow for a much more streamlined experience.