Hello!
I'm WHMCS admin user/developer already since v2.2 (somewhere in year 2006), did many template customization, hacks & hooks, provisioning modules and payment gateways (last was The Ethereum and bitcoin payment gateway for WHMCS 7.5.2).
I would love to create a module for Twillio SMS based 2FA.
In matter of fact, In the past i have implemented twillio in WHMCS to send payment confirmation for affiliated users.
Please PM me to discuss the details.
Looking forward working with you,
Mathew