I’ve been looking for the recommended system requirements for Lubuntu but couldn’t seem to find anything in the manual or the wiki. All I could find was a page on Ubuntu, but warned me that the information might be outdated.
From the Lubuntu blog is this post - https://lubuntu.me/taking-a-new-direction/
This means that Lubuntu will stay light, and for users with old systems, should still be usable. But we will no longer provide minimum system requirements and we will no longer primarily focus on older hardware.
I used very old boxes in my testing of Lubuntu 18.10 & 19.04 (until x86 ISOs were stopped Dec-2018) which included single-core pentium M with 1GB of RAM laptops, but these days laptops that old are obsolete. Yes 1GB could run Lubuntu fine, but I had to use the laptop somewhat more restrictively that I do this, my main desktop (with 8GB).
Minimum specifications don’t mean that much unless they match your use-case (how you use the box, you use the same apps and in the same conditions); and whilst I could do what I do now on 1GB of ram, I’d not want to (I’d want to change a few of my preferred apps for starters).