Another answer already gave you the information you look for, but this is really just a case of "politics makes strange bedfellows".

Russian government officials want to replace Windows with ReactOS because they want Russia to be independent from US companies like Microsoft.

I want to replace Windows with ReactOS because I believe in free and open source software as a movement for individual freedom.

We are not the same, but can still work together on something practical like this.

In 2007, then State Duma member and chairman of Russian Center of Free Technologies, Viktor Alksnis met with project coordinator Aleksey Bragin, who gave a presentation and demonstration of the project, showing ReactOS running with Total Commander and Mozilla Firefox.[42]

In 2011, a demonstration was given to then president Dmitry Medvedev during a visit to a high school in Verhnerusskoe, Stavropol, attended by one of the development team members.[43] On 31 July 2012, Vladimir Putin was also given a demonstration during his visit as President of Russia to Seliger Youth Forum, attended by Marat Karatov, one of the development team members.[44]

On 1 April 2015, Bragin attended an expert meeting of the Russian Ministry of Communications on reducing Russia's dependency from proprietary software imports. Its minutes name the "creation of an open source operating system based on ReactOS for PCs, laptops and other mobile devices", as well as the "creation of an open source operating system for servers based on ReactOS",[45][46][47][48] placing it second among three named proposals.

https://en.wikipedia.org/wiki/ReactOS

It’s a Russian software, built in Russia and by mostly Russian developers. It’s also being pushed on the Russian government to use it instead of vendor lock-in. I don’t know as a matter of fact that was “Putin-endorsed” because all of my knowledge about it is from the internet. But yeah, it’s Russian. Also

It's not "russophobic" to hate the current fascist government of Russia.