The app is still available in other countries, so in order to install it in Russia one just have to create another Apple account to install it from a foregn app store on the device.
"Just" creating another Apple account means forfeiting all your data, apps, purchases etc. There are many simpler ways to access that same data, for example on navalny's website via a vpn. But all those ways are too complicated for most people.
That's not how it works on iOS. iCloud and App Store accounts can be switched independently. After the installation you can switch back to your main account, and all your data will still be there. Newly installed app should auto-update as well.
I personally have apps from 2-3 different countries' store accounts on my Apple devices.
