How to evaluate the price of the quality of application development?

Question

Project management

I'm going to order the development of an application for the company (the design is made), you can estimate the amount of work by the prototype https://www.figma.com/proto/WBUdRGw5MjhBVcGO5bR9fW...
The server part is on our side, there are also php programmers and layout designers on staff, the content of the article it is supposed to be done in the form of html (the longest page in the prototype). A freelancer is required to have a native application for android.
Questions:
1. How to evaluate the cost of development
2. How to evaluate the quality (both works that are in the portfolio and the work received) * evaluate it in terms of code quality, not design, ux, etc.

Answer 1

1. See how long it takes. Cost, respectively, in man-hours (very approximate)
   PS
   IMHO now it makes no sense to immediately make native applications. If you don't need speed, it's easier to use PhoneGap and adapt to all platforms at once.
   Less labor and less wastage if the project doesn't go off the rails.

Answer 2

How to estimate development cost

If you are not an expert in this matter - no way.
As an option - ask to evaluate another person who is a pro.
No way.
Similarly - ask to evaluate the pros.
Based on the fact that you ask this at all, the option of hiring a pro is suitable for you to evaluate it.
You can give two or three strangers, give a few estimates - for a guarantee.