Inkscape contains an impressive quantity of features - and that is one of its problems! My artist wife's first concern is to produce artwork, at present in the form of cartoon strips or illustrations for children's books. In order to get started on her latest projects she has been attracted by some of the simple doodling applications such as the one in OneNote, but of course to go further she needs to use vector graphics rather than bitmaps. For several decades now she has adapted to the increasing complexity of the Corel graphics suite, tolerating rather than welcoming the new features that push up the price. Inkscape can do all that Corel can do, but finding a way through the menus can be a problem.
My first suggestion is that you show a 'newcomer' option when the software is first loaded. Only three or four pen settings are offered and most of the other tools are hidden. On the basic pen, pressure changes width, rather than opacity. Instructions and hints are directed to enabling more of the features - when the user is ready for them.
Find an artist friend who knows nothing about graphics software, if you can, and watch them as they start to use Inkscape.
Best wishes John