Yes, no one will sue you because your product has the same form factor and pin layout (electronics manufacturers make pin-compatible parts all the time), and since the Google vs Oracle trial API's shouldn't be seen as copyrightable (at least, in the US). So no problems there.
The main question however is: how are you getting your certification? If you make or sell or use Lorawan transceivers without LoraWan or CE certification, you put your business in a VERY risky position. Adhering to the layout of a CE certified chip is NOT enough to claim CE certification, let alone LoraWan certification by the LoraWan Consortium. All it would take is one claim from a competitor to potentially put you out of business. This is why the RN2483 is such a popular chip: it's a fully LoraWan and CE certified part, and businesses need to have that certification if they want to comply to regulation.
Building your own RN2483 module for a lower price is nothing special, I could probably design the part and write the firmware in under a day. It's also what most hobbyists do: buy uncertified RFM95 Lora transceivers for €2/piece on Aliexpress, throw in €5 for a microcontroller and some components, compile the LMiC LoraWan library et voila, your own fully functioning LoraWan transceiver for less money than two beers at the pub, and made in less time than finishing said beers. Is it technically usable? Sure is. Would you want to use it as a company? Hell no. Having someone already taking care of the certification for you is more than worth the few extra euro's/dollars you have to spend at a RN2483.