yes, this is possible and lot of our customers do so. I have attached a "How To" Documentation to create your own widgets.
Some of our customers also use Angular, jQuery or other frameworks, so its possible. But sorry we cannot support all of them, maybe someone could send us examples here in this forum.
Via the login area on our website (smart-hmi.com) you can find other interesting developer manuals, HowTos, download examples e.g. for a ChartJS widget and much more. You just have to register beforehand