Only Google can add new categories, so you will have to choose within the categories available. Google adds and removes categories every month so your category may be added at some time.
Tips to choose the right categories for your profile:
- Check your competitors for ideas
- You can get all available categories from here: https://pleper.com/index.php?do=tools&sdo=gmb_categories
- Check every month if the category you want has been added
Request Google to add a new category
If a missing category is holding your business back, I recommend adding a thread to the GMB help forum, making the most convincing argument you can about why Google needs to include the category you wish.