Customisable UI

The idea behind Sailfish Silica is to keep the 'theme' as light as possible and not to have large coloured buttons, headers, footers, backgrounds, etc, eating up what little resources the device has....all this will serve to do, is cause system and UI lag.

Ambience is slow in development, not much has changed since the launch of the device 3 years ago. It is unlikely that Sailfish will ever support themes other than 'Ambience', unless it is end-user created.

There is a theme app on Openrepos by fravaccaro; https://openrepos.net/content/fravaccaro/theme-pack-support-sailfish-os , but this only supports changing app icons, fonts and sounds.

Ambience packages were really designed to be 'purchased', meaning that you would buy a TOH (The Other Half) and get to download the new ambience containing its sounds/wallpaper/etc.

I think we will all be waiting sometime for anything to happen with ambience/themes on a serious level, it doesn't appear to be one of Jolla's priorities and please remember that Jolla are only a small company/team and there is so much in other areas of the device that still needs work....don't hold your breath.