How to properly prepare icons for a native application for mobile platforms?

Question

User interface

A collection of icons for the application has been prepared, the icons are made in vector.
You can export to SVG, you can also cut to PNG.
How to correctly issue a collection of icons for developers of mobile applications (ios, android) and in what format?
There are many places where they write that uploading to PNG is common, such as @2x, @1x, etc...
Isn't it considered good practice to use graphic elements in native applications in vector formats, such as on the web? After all, if you use SVG on the web, then the load is reduced and it looks more and more elegant. Isn't that the case with mobile apps? How right? What are the capabilities of mobile development platforms? What is the best thing to learn and be able to do so that developers and customers are always satisfied when you provide them with the result of a mobile application design (psd, png, svg)?
Modern development technologies and the latest libraries that are used in mobile applications, how do they work with graphic elements? What are the principles and foundations?

Answer 1

Not so long ago I tried to use .svg images provided by the designer. After a couple of hours of swotting, it was decided to make some pictures in .png format with the size corresponding to Apple's guidelines. Dropped it off and started using it within 3 minutes.
So in the case of iOS, .png is definitely the best choice.

Answer 2

The use of vector images on phones negatively affects the smoothness and responsiveness of the interface. Therefore, for the highest speed of applications, it is worth using the most ready-made icons.
(no resizing, coloring, etc. in raintime)

Answer 3

What is the best thing to learn and be able to do so that developers and customers are always satisfied when you provide them with the result of a mobile application design (psd, png, svg)?

Learn and be able to ask the customers themselves.