It would be really convenient to have Kile as flatpak given that org.freedesktop.Sdk.Extension.texlive exists. It is a single package containing all texlive packages, which is simpler to update than hundreds or thousands of repo packages. Not depending on limited repository packages is also convenient for smaller distros. TexStudio, TexMaker and Setzer are already available as flatpaks, and they can make use of this.
I found a github repo with kile flatpak here, not sure why they did not submit it. https://github.com/KDE/flatpak-kde-applications