Inkscape, Adobe Illustrator, Cad, Vectric (Cut2d), Silhouette etc are all at a basic level the same shit with a different skin. Some might have an extra feature or two that makes buying it better (nesting doesn't exist in Inkscape for example), but there are also free web services that can do that too.
One app may call it grouping/ungrouping, another calls it join/unjoin, merge/unmerge, but at the end of the day all the shit is the same with a different naming convention. Start with inkscape as its free, and if they can design a few shapes relatively easily and understand the concept of stuff like subtracting an object from that or merging it with another to create a different shape, they can do most anything.
YMMV, but my one stickler point that determines what app I find useful is just dumb basic shit. As an example, in silhouette mousewheel doesn't zoom in and out, it scrolls the screen up/down and you have to hold control to scroll left/right. For me, that is the most annoying shit ever, and while likely something you can fiddle with in the settings I couldn't be bothered to.