alt Hacker NewsKnoppix was the first Linux distro I ever tried back in the early 2000s. IIRC it was only a few hundred megs.
At the time it didn't have the overlayfs feature which often felt limiting since most directories were read only. Slax felt like a serious upgrade since you could install more packages after booting the CD.
I think Knoppix was the original live CD distro though?
I remember running live and then installing from Yggdrasil in the early 90s on 486 with 8MB RAM and 250MB hard disk.
https://en.wikipedia.org/wiki/Yggdrasil_Linux/GNU/X
Really liked Knoppix for a lot of things, though. Used to take it to the county used-sales office and boot the PCs they were selling to test for functionality and Linux compatibility.