Use private key file from Windows?

[Utini2000]

Is there any way to use the private key file from windows which is usually stored in one of these directories:

• C:/Users/Username/AppData/Roaming/Microsoft/Crypto/Keys/
• C:/Users/Username/AppData/Roaming/Microsoft/Crypto/RSA/S-1-4-21-...../
• C:/Users/Username/AppData/Roaming/Microsoft/SystemCertificates/My/Keys/

The certificate I am trying to copy from windows to linux is created with the flag "private key not exportable".
But it seems like the private key is just laying in the folders above.
How ever, it isn't a .pem file and openfortivpn throws an error when trying to use it as --key-file.

Thanks!