Very keen to see calligraphic brushes implemented in Affinity Designer! I know this is on the current feature request list, but just giving it a vote, and hoping it will make the next version.
I do like the Illustrator implementation, where I can modify the brush by rotating the elliptical stroke profile, and view the calligraphic effect on the stroke live.
At the moment, I need to do this in Illustrator, then expand the outline and copy / paste, export / import / open in Designer, and this process invariably makes a bit of a mess of it by adding numerous bezier points.
I have experimented with the "Pressure" option in Designer's Stroke palette, but this obviously is not intended to be the same functionality.
Thanks!