I contacted Asus technical support and they told me to contact the Asus E-store. I emailed the E-store and they told me they didn't have anything.
Based on this, I don't think anyone knows if there will ever be an appropriate TPM available.
MSI makes a 14-1 pin TPM, but I compared the pin assignments in the Asus and MSI manuals and they are different, so they are not compatible.