pfSenseDUO - What package did you purchase? you might need the API / APP plugin for this.
I am a network and cyber-security engineer with 20 plus years of experience. I have been employed by companies such as Cisco, Dell, Sonicwall, Palo Alto Networks, Lancope, Fortinet and etc. I can help in configuration, services, advisory and consulting with networking, datacenters, security, wireless and etc. I have a wide range of certifications from CCIE, Blockchain Certified to GPEN (Certified Penetration Tester). I am also a public speaker for major conferences such as DefCon, Blackhat, GITEX, Cisco Live and RSA. I would be honored to chat with you about your project and set up a time to see if I am a good fit. I can set up a Cisco Webex Meeting when time is right for you.
I am interested in this and never thought of this before. The Yubi key is easy as any user can use that for MFA. That is more of a user end setup than an admin. Regardless I can get this set up in my lab with PFSENSE and attempt to attach DUO to it. Its important that I know what package you purchased as they are limited based on what level of product you have. BTW, I work for Cisco/DUO so I have endless resources to make this work. But I will be honest and let you know if this is NOT possible. Thanks