Chromecast setup is very similar to a Firestick setup
however devolper mode is different spot
To enable developer mode on a Chromecast with Google TV, navigate to Settings > System > About, then click on Android TV OS Build seven times. This unlocks the Developer Options menu, allowing you to enable USB debugging and install unknown apps/sideload apps.
please see this video https://www.youtube.com/shorts/zO4jlRGwVhw