Someone in HN said GNOME and Plasma are evolutionary dead ends for mobile. I kinda agree these are a lot less elegant than Mer (SFOS and Nemo). FuriOS is based on Phosh (GNOME), so that makes it less attractive from an UI perspective than SFOS.
The major problem right now seems that no Linux mobile platform offers what MeeGo was offering around 15 years ago: a mainstream browser (Firefox), VoIP (SIP, Google Talk and Skype), and offline Maps (Nokia).
SFOS offers these items, but it requires piggybacking too much on Android. Having Android compatibility is good for edge cases, but the core of the platform should be native.