Aren’t ThinkPads dual channel ram anymore?

For the 64 bit, Fedora LxQt works very nicely on a 2GB Ram PC. I’d suggest you avoid Lubuntu as the snaps are not very lightweight as you begin installing more and more. Debian LxQt would work as well, but it wouldn’t provide any advantages over Fedora and its packages would be less up to date.

For the 32-bit one, use Debian i686.

Another option, of course, is to pick Arch and Arch32 and build a functional system from there, but there are little guarantees that the 32-bit one will work, given patches have to be done to software in order for it to compile to i686 PCs.