The editor is windows only, but you can export for all these platforms, including osx.
A Stride project is just a normal visual studio solution, so you can build the solution on other platforms too, if you don't use the asset compiler, which is also a windows only application.
A Stride project is just a normal visual studio solution, so you can build the solution on other platforms too, if you don't use the asset compiler, which is also a windows only application.