MS owns Typescript and NPM and Azure and LinkedIn. I know you meant programming on Windows, but even if Windows disappears, many of us will owe our job to Microsoft.
They own Typescript? I wasn’t aware that they control the organization, but that ought to be easy enough to fork. NPM is a bigger one, but also not too huge. Azure is only used by people who already have Microsoft/Windows buy-in.
Dont forget they own github too. The vast majority of open source software is on there these days.
Yes there are other options: gitlab.com, some project specific gitlab instances (freedesktop for example), forejo / codeberg, and the Linux kernel is off doing it's own thing with mailing lists instead. I even come across code on SourceForge every now and then still. But all of these are super niche.