we really must distinguish between portamenti and glissandi. Although it’s of course far from a hard and fast rule, port. tend to be mainly associated with strings and glissandi – which is more of an even slide often over a larger span – is something which can be particularly effective with brass.
The main point is that sample libraries mostly support portamento and thus by definition is supported by Dorico as the patches are present. Glissandi are supported to a lesser extent, for instance by having just an octave or other option or frequently none at all. It is here where Dorico could really make a contribution with a simulation and the current stepwise movement is seldom of much use so I’m a bit disappointed also it hasn’t made it into this release.
Just one question – NotePerformer does have built-in support for glissandi unlike most conventional libraries and this works very nicely in Sibelius. Is it to be assumed that this as well won’t make it into the initial v4 release? Here things may also depend on Arne and it seems rather quiet over there these days.