Re: Really small systems
To be more specific, netbooks used to have have 2-4GB RAM. These numbers look like re-purposed Windows netbooks.
Windows 8 era netbooks also came with eMMCs of typically 32GB of size, which is patently small for W10, but is plenty for Debian or Ubuntu.
History:
I have a HP Stream x360: https://www.theregister.co.uk/2015/04/06/review_hp_stream_x360_convertible_laptop
1366x768 screen, Celeron 2-core, 2GB RAM and 32GB eMMC. All soldered to the board for zero upgradeability.
I ran Debian on it, until GNOME bloated itself out of the RAM. I guess Ubuntu might still run on it.
However, I opted to buy a bigger machine instead.
Originally, the Stream came with Windows 8. But even the original installation used up 15GB of space, and W10 sure didn't get any smaller. So, a lot of the Ubuntu installations may be similar post-W10 throw-aways re-purposed.