I thought i’d post this up as it’s not included in anyones tutorials via Youtube or text - though i’ve seen one person mention it happened without realising.

If you’re moving to another SSD and are cloning using “dd” in SteamOS to the external drive that is bigger you do not need to adjust the partition size afterwards. It will appear in SteamOS EXACTLY the same as the cloned drive - so if it was 512gb and you’ve cloned to a 2TB drive, it’ll show you a 512gb partition.

However install it in your Steam Deck and upon first boot SteamOS will expand the partition for you with no extra work required. Easy!

2TB Oled Steam Deck now running.