Not sure what you're trying to do in keyboard layouts. I've yet to encounter the flexibility for keyboard layouts that you have in linux in any other OS.
Regarding email clients, again I'm not sure what you consider feature complete, but even some of the proprietary options like mailspring or hiri exist on linux.
For calendar it again depends on what you are trying to do. I've recently started using Minetime, which is not OSS but free and is working very well for me.
One of the weird phenomena that I find in these discussions, is that people are often happy for proprietary software (like OSX or windows) to restrict what they are able to do, and having to adjust their workflow to these systems, but when it comes to OSS suddenly not being able to match the previous workflow, makes the system unsuitable. (Note that this is not aimed at you directly, just a general observation).
Regarding email clients, again I'm not sure what you consider feature complete, but even some of the proprietary options like mailspring or hiri exist on linux.
For calendar it again depends on what you are trying to do. I've recently started using Minetime, which is not OSS but free and is working very well for me.
One of the weird phenomena that I find in these discussions, is that people are often happy for proprietary software (like OSX or windows) to restrict what they are able to do, and having to adjust their workflow to these systems, but when it comes to OSS suddenly not being able to match the previous workflow, makes the system unsuitable. (Note that this is not aimed at you directly, just a general observation).