Ah dang, being so used to having the OS on nvme0n1 nowadays instead of sda, my brain autopiloted a dd call to overwrite the first 1.5GB of a system disk and it only clicked on what happened after spending a minute trying to figure out why it wrote way too fast for the slow little thumbdrive I wanted to image and seeing the GPT mismatch error in fdisk :floofWoozy:

But I'll never not be amazed at how long a running Linux install keeps working after its root disk has been overwritten with garbage!