I'll reiterate what I posted in "The Great Machine" comment section. The official omnibuses from Kodansha Comics USA contain oneshots at the end of every omnibus from Kishiro's early days as well as some oneshots made during Alita's initial serialization, if that interests anyone.
As an addendum, the Kodansha omnibuses are collected versions of the Viz translation from the 2000s, which is noticeable by how the SFX are translated (which is unusual for Kodansha unless it's Ichi-F or Vinland Saga), and because it's a 2000s translation there'll be some wonkiness (still reads fine for the most part, however). The single tankos from Volume 16 and onward are completely new translations and releases from Kodansha as the contents from those were serialized in their "Evening" magazine.
Just thought I should let everyone know.