Answer 1, Authority 100%
in no way. This authorization option is denied, only the standard SDK window.
Most likely, this can be achieved or a crutch of the type of the hidden browser inside the application, or being somehow an incredibly trusted application for a wig. Here you will most likely help support (help, and it will not give out this right:)).
p.s. At one time, I wrote in support of Will and they said that it was impossible to create your own authorization window. To the question why Kate Mobile has such a window, they replied that they were given the rights for a long time and “on other conditions” (what the conditions did not understand).
Access to direct authorization is issued by the VK administration. Here it is written in more detail: https://vk.com/dev/auth_direct