Thanks to the information from https://dexterposh.blogspot.com/2015/01/powershell-rest-api-basic-cms-cmsurl.html, CBA for WS1 is possible cross-platform in PS Core.
However because the CMSURL scheme requires the $uri.absolutePath of each URI as part of the header itself, every API call needs to be able to use this.
The result of this is going to need to be a function that converts the Header to the CBA version. This function will need to be called within every single WS1 cmdlet if someone specifies a -CertificateAuth parameter.
This probably should be called
convert-ws1CertBasedAuth or such. The input is the $url fo the API call, the output will be the CMSHeader found in Dexter's function.
Regression testing is going to need to be done for every cmdlet to add this in.