I have a two-in-one laptop (Dell Inspiron 7348) with a touchscreen and a touchpad running elementary OS 5.0 Juno and the pinch-to-zoom gesture works ok on the touch screen (but still not very fluent). But if I do the same on my touchpad, nothing happens.
I have now installed libinput and libinput-gestures and tried it that way but its not very satisfying because it is only capable of triggering the zoom key and thus zooming once per pinch and not corresponding to the pinch. I only found out that it works on the screen after I installed libinput-gestures and have now deduced that there must be a way to get that working pinch-to-zoom feature from the touchscreen to also work on the touchsceen. I am sorry if this is a dumb question, Juno is my first Linux ever.