At the moment both right and left dragging inside the Navigator act to drag the view area.
Feature request for right-mouse button or right/side pen button (mapped to right mouse button) drag to zoom (left to right or down to up zooms in, right to left or up to down zooms out).
A slider would be more straightforward. There are some technical reason I haven’t put it in so far, the main being that it wouldn’t work smoothly due to occasional composition update at some zoom level. Well I can try it to see if it works good enough…