Another thing publishers can already do is reduce the size of their snap. This has a significant effect on startup time; the DBeaver snap startup went from 6 seconds to 3 seconds, simply by reducing its size. I have had similar success with other snaps such as Foliate and Minecraft Installer.
I took this opportunity to start a page in the docs about reducing the size of desktop snaps. Let me know if you have more tips. Feel free to add them to the page; it should be editable by anyone.
