These are just the leaked ones now official, right?

These are the official ones, yes.

Time and again, the following problem appears (with pretty much any nv drivers lately): upon the execution of the driver package (xxx.exe), driver starts installing, then it gets stuck and reports the "failed installation". Now, if I unpack it (using 7zip or WinRar) and extract all files and folders into a "temp" folder, and I launch the installation process by executing its "setup.exe", the installation goes all the way up, without any issues. And it is NOT system hardware/software related - I'm having this problem on a few PCs, with win7 and/or 10. Anyone knows WHY? Is it possible that the guys at nvidia aren't capable of putting those files into a decent self executive?

Because you altered environment variables.

Which one(s)? And even if it is so, then why it does not happen when launching any other self exe file?

These are not on the nvidia.com website so not sure how they're official

oli3:

These are not on the nvidia.com website so not sure how they're official

Their site doesn't list any beta driver for the 10 series on Win 10 64 aside from a single one from 2017.

DLD:

Which one(s)? And even if it is so, then why it does not happen when launching any other self exe file?

Temp directory needs to be default, or junctioned to an alt drive instead of using path redirections.