Setuptools: pip uses host platform for its environment markers

In requirements.txt you can specify environment markers to conditionally select some wheel or not, for example :

pywin32 ; sys_platform == 'win32'

However, when cross-downloading like setuptools is doing, pip still uses the host platform for the environment markers instead of the platform specified on the command line (there is a change request open on pip

The only workaround for setuptools looks like to have separate requirements.txt and also separate, one for each variant of dependencies ?