Does anyone managed to implement push notification authentication with Keycloak with free tools? Have open source code for an app or SPI implementation?
I would say it will be tricky: you will need to manage own mobile apps/keys/… (unless you want to kill battery of mobile devices and use long pulling). Good start will be AWS SNS mobile push notifications.
A lot of work, so I would say SaaS will be better, e.g. GitHub - mulesoft-labs/keycloak-duo-spi: Keycloak integration for Duo Security MFA