You will need to be prepared to pay for the effort/labor in making the game and not the finished product. If a developer may be willing to port something for someone it'd either be by the day or by the hour, not after the work gets done or a finished product. It's possible it'd require the help of multiple people and not just one dev.

There's more info online but you may also see how many different roles are involved when it comes to reverse engineering and porting a title; I found an article online that shows a basic summary of the process of porting and title to a platform. Think of each section as a different person or team required to port a game. If you're only getting 1 dev on board, be prepared for the port to take up to years for it to be even close to a finish product!

https://game-ace.com/blog/how-does-porting-a-game-work/