I don’t suppose you could install your own SSHd, and have it automatically run PowerShell upon logging in? Or default to the standard Command Processor? (or even go for broke, and install one of the many UNIX shells for Windows—the Bourne shell comes to mind)
The SSHd installer would have to be self-hosted (no MSI, obviously)
I generally have used the sshd that comes with Cygwin, which is bog standard OpenSSH and works quite well. OTOH, it assumes Bash for its shell, and while you may be able to spawn PowerShell automagically, I don't think that's what you're suggesting.
Certainly seems that somebody ought to have done this already....