In the Tampella 5.0.0.55 thread Jolla say they’ve been fully occupied with the C2 and Jolla Mind, so I guess other things have been de-emphasised for now.
I also thought the 5.0.0.55 release was more like a small bugfix point release (i.e 4.6 → 4.7) rather than a major OS upgrade release, as aside from the new browser engine (done by a community member, no longer a Jolla employee), landscape mode for some of the existing Jolla apps, and a call blocking feature added to the settings of the phone app, there appears to be little different from before in terms of new functionality of SFOS.