mark47 - I'm more than sure that you can find a company on the internet, just check the reviews beforehand to find a trustworthy one.

blind - It really depends on the company you'll work with, and that's the reason why you should be careful choosing specialists to work with. You can check out https://apiko.com/industries/e-commerce-retail-marketplace-development/ and learn more about these guys, they're actually good at providing custom development services, and you won't be disappointed if you decide to work with them.

evan05 - If you need to develop an app for business purposes, I especially advise you to start with this article https://www.erised.io/blog/how-do-i-build-an-app-for-my-business . It seems to me that those who are new to application development should definitely familiarize themselves with the various stages and generally learn more information.