For people asking for a way to run 2fa on jellyfin i have a solution. I will elaborate more if people are interested as not writing a guide for no reason. This method allows users to simply use their login credentials into the default jellyfin login page, and 1 second later your DUO app on your phone will buzz for a confirmation to sign-in. (meaning no redirects and this method 100% compatible with all clients)

install the LDAP plugin on jellyfin. install Authentik in your server with docker. create a DUO security account. in short, jellyfin query's your Authentik LDAP server for ther user login, then LDAP will query DUO.

Unfortunately, DUO only allows 10 users with the free account, then you have to pay extra. of course with this method you are not bound to only use DUO, you could you a web-auth with your phones bio-metrics to sign-in instead of DUO. there are many ways you could query the users phone through Authentik, but DUO is the most continent.