With Bash on Windows you'll be able to run Linux apps on Windows too. So, if that works out Windows lock-in would be about even with macOS. Lower, if it works really well since hardware is no issue. But that's as a desktop workstation.
This is about the cloud and servers, so Macs don't really apply. Despite the apparent lock-in, Windows is still a great server choice for small and medium sized businesses, even in the cloud. Switching away from say SQL Server to something like Postres isn't that hard. Things only get difficult if you use features like Active Directory integrated authentication, Sharepoint integration, Exchange, etc.
EDIT: I wouldn't switch though. Not for a cloud app that is to be managed by most small IT departments that I run into. SQL Server is so much easier to work with and manage than Postgres due to many seemingly insignificant features including a kick-ass GUI, stored procedures, returning multiple resultsets from a single round-trip query and the fact that it runs on Windows, which is still the number one OS used by the market that I serve, even in the cloud (but mostly for B2B or operations). These are the same sort of reasons that I build their back-ends in IIS/ASP.NET (despite the fact that I also use Node.js heavily for my own projects and I even use it to generate static files for my ASP.NET projects).
This is about the cloud and servers, so Macs don't really apply. Despite the apparent lock-in, Windows is still a great server choice for small and medium sized businesses, even in the cloud. Switching away from say SQL Server to something like Postres isn't that hard. Things only get difficult if you use features like Active Directory integrated authentication, Sharepoint integration, Exchange, etc.
EDIT: I wouldn't switch though. Not for a cloud app that is to be managed by most small IT departments that I run into. SQL Server is so much easier to work with and manage than Postgres due to many seemingly insignificant features including a kick-ass GUI, stored procedures, returning multiple resultsets from a single round-trip query and the fact that it runs on Windows, which is still the number one OS used by the market that I serve, even in the cloud (but mostly for B2B or operations). These are the same sort of reasons that I build their back-ends in IIS/ASP.NET (despite the fact that I also use Node.js heavily for my own projects and I even use it to generate static files for my ASP.NET projects).