I already cloned my launch Deck onto a external hard drive with Clonezilla a few days ago. Realized i didn’t have the correct size torx screwdriver, so i had to wait a few days to get one. I’m going to open up the OLED to put in a 2 tb SSD, and then use Clonezilla to install my Deck image. Should be no problems, right? Firmware was updated a few days ago, so it’s up to date. I think it was 3.5.5 or something.
You may need to grow your home partition to take up rest of the empty space in the drive. You can use gparted to do that.
SteamOS does that automatically. You don’t need to do that manually.