There's a closed bug on this (#199), but the premise for closing the bug is not valid since AppCenter apps don't have to be coded in Vala. See excerpt below:
We frequently get asked if developers can publish apps written in languages other than Vala or with a build system other than CMake. The answers is “yes”! All of our documentation is built around the “one true development path” that elementary follows, but as long as your app is a native Gtk3 app with Debian packaging, it should be publishable. Several apps published in AppCenter are already using the Meson build system, for example.
Source: https://medium.com/elementaryos/so-you-wanna-publish-on-appcenter-12c675b56e1c#aec2
AppCenter also uses debian packaging, which already exists for ulauncher. Should not need many additions to submit to AppCenter.
Looking for contributors who can figure out how to package for Elementary OS and provide either a proof of concept or a step-by-step guide.
@gornostal if you have Debian packaging already it is a matter of integrating with their CI (Houston).
@CameronNemo thanks for the info
Seems we are at the point of needing to write the appdata file, as described in this section of the elementary publishing/packaging wiki.
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AppCenter also uses debian packaging, which already exists for ulauncher. Should not need many additions to submit to AppCenter.