To install Google TV on a USB drive, flash the Google TV ISO to a 16GB or larger USB using Rufus, set maximum persistence, then convert the persistence partition to exFAT. Move system.sfs and data.img ...
The loop of recreating a bootable USB drive for every reinstall or troubleshooting became unbearable for me. I switched to a Ventoy drive a long time back, and it's saved me so much time. Before that ...