Internet != Web
What is not so easy is replicating equivalents to the entire very sophisticated ecosystem of the current internet. Databases, APIs, software, services. Is it possible to maintain rewritten-from-scratch equivalents of google, AWS, azure? I doubt it.
Equivalents of google, AWS, azure? Do you mean like the Alibaba cloud? If you want to do similar yourself take a look at libvirt and kvm. There are plenty of tools to manage a kvm/libvert cloud (including Terraform Libvirt provider)
Very sophisticated ecosystem of the current internet? Everything that makes the core of the internet work (whois, DNS, BGP) is open source.
parallel software ecosystem - IOS? Not everyone wants to use Apple phones. There are plenty of Android ones and there are alternatives to the Google Play store.
parallel software ecosystem - Windows? As for Windows, does windows stop working if you NEVER activate it ? For the home user it's almost like shareware / nagware back in the day... You really should register this product so you don't have to look at this licence screen.
parallel software ecosystem - Office? Libre Office? I'm sure there are other open source equivalents.
parallel software ecosystem - Databases? Where to even start with this one. Most SQL databases are open source. Take a look at PostgreSQL or MariaDB for just the most well known. Yes there are also ones like CockroachDB which are propriety but I imagine that all it would take is one purchase for all of Russia, especially as Russia is decriminalizing software piracy. All of the main document databases are already open source.