In one of the SP2016 feature packs they added the ability to add custom tiles to the AppLauncher, getting it going is decently documented here:
One thing that isn't clear to me and that I learned through troubleshooting is I had an issue where most of the users if not all didn't see the custom tiles that got added. This was after both using the
ClearSuiteLinksCache() function in browser and waiting 24 hours.
I tried a couple of things, like granting everyone read-only access to the applauncher and images libraries in central administration (but obviously not publishing links via email to the libraries). I assumed the reason people didn't see the links was because they didn't have permissions. I actually am not able to confirm at all if this is the fix because I saw inconsistent behavior across peoples machines.
Does anyone know what the exact requirements are for getting the tiles to definitely show up across site collections in a separate web application from central admin? Assume that I've followed all of the steps in the MSDN article correctly.