I was able to upgrade from Lubuntu 16.04 to 18.04 for my 32bit IBM Thinkpad T42 using do_release_upgrade. It’s not downloadable on the website, but I think for 18.04 the build is still there.
I think they've stopped building them in 19.10. 18.04 is an LTS supported for 5 years, so users of i386-only CPUs are fine until 2023.
I have a load of 32bit laptops, "I'll put ChromiumOS on them", nope, that's not a thing any more. OK, err Linux? Apparently not. Could put Windows 10 on them I guess.
You could try Debian, which is essentially Ubuntu minus some themes. I doubt Debian will drop i386 support soon (I just searched and couldn't find hints of an end of support of i386)
But then you'll have all these kernel bugs.
What do you mean?
Ubuntu is a Linux, but Linux is not only Ubuntu. I have loads of x86 boxes - Debian, Puppy Linux, whatever. (Win10 has a 32-bit option? Whoa. #TIL)
Lubuntu 18.04 (and most other Ubuntu derivatives like Xubuntu etc.) is only supported for 3 years.