I don't think it is the right place to find an application developer because the majority of moms here are associated with blogging. I would recommend you find app developers at UpWork, but you would have to be very careful about making an offer. Similarly, other freelancing platforms like Fiverr, LinkedIn Pro Finder, and We Work Remotely are also good places to find app developers.
On the contrary, if you have some knowledge about frontend app development, then why don't you go with serverless development platforms like Firebase? Yes, this development platform could be the best choice for budget-centric and speedy app development queries. By the way, you can also visit top programming forums and can ask for a good app developer. It is also a good way to find a good app developer.