I don’t have an ipad and I haven’t used Vectornaor, however, I use Affiinity Designer and when drawing artwork with a stylus the lines smooth too much. Here is my translation of what I found out when I got completely frustrated trying to create drawn art in a vector program:
There should be some sort of “smoothing” setting which can be adjusted up and down, and Affinity has a choice of 2 different ways that it smooths. in Affinity, this can’t be zero.
Vector programs are not Paint programs so work differently with how they handle your pen strokes. Vector programs lay down nodes and you can change the “bendiness” of the lines by moving nodes and adjusting the handles to shape the curves. Once you draw your line, have a look at the nodes and see what it did to “help” you. I was drawing ovals and the software was only creating 3 nodes - they didn’t end up looking like the oval that I drew.
I found that I couldn’t draw artwork in Affinity Designer in the vector mode, I had to change to paint mode (I don’t think I have the names right…). This results in not having vectors, but having an outcome that I like that is digital.
What artists do to create vectors of their artwork is to import it as a jpg / png / whatever and then trace the artwork with the pen tool and adjust the nodes to create vectors of it.
In short, you may not be able to draw exactly what you want in a vector program, but you should be able to adjust the nodes and / or trace an image to get a vector.