Note: not ordered. do whatever I/you want

+ Cookbook of basic things
+ Write good help/manual
+ Make error notice short while let users see detailed help/manual for what-to-do
+ Even better CUPS/IPP support
+ Even better frontend usability, more functions
+ Make a build guide for android:
  Summary the hacks to p4a, bleak p4a recipe, p4a webview bootstrap, and AdvancedWebView
+ Try to implement enough without more dependencies
+ ...

? Optimize PF2 text printing? It seems a bit slow (in algorithm).
? Built-in PostScript? (Even if very basic)
? Data compression for GB03. Optional
? Put Android APP on F-Droid? But it needs automatic build system...
  Android guys can help this!
? ... Or put to APKPure?