Parallelized service start on desktop boot and other similar desktop boot optimizations come to mind.

But yeah, mostly it's the remaining 80% work of polish (in the sense of the adage of the remaining 20% actually being 80%) needed to make a Free Software system usable by the masses. Lots of work and lots of value but this doesn't involve significant technical advances, just hard work by smart people who truly understand the whole stack technically but are also able to see from the perspective of ordinary users.

Canonical also pioneered Launchpad and Bazaar. Today they are eclipsed by GitHub and git, but at the time they led in Free Software distributed development tooling. Early GitHub was apparently modelled on Launchpad for example. There's a really interesting retrospective that explains a lot of what you see of Canonical and community and contributions here: https://www.jelmer.uk/pages/bzr-a-retrospective.html

Oh, and container technology. You'll need to look into the details of that to understand exactly what Canonical did and didn't contribute, but Canonical's contribution was significant.

> NIH

If you look into the specifics most of the things commonly cited as Canonical NIH predate or at least were already in progress at the time of the alternative.

Disclosure: I work for Canonical but wasn't involved in the work cited above.