There are a few more helper functions worth mentioning. If you need to generate a pseudorandom color for some element, use the kanban_color(some_variable) function, which will return a CSS class that sets the background and color properties. This is usually used in t-att-class elements.
If you want to display an image stored in a binary field, use kanban_image(modelname, fieldname, record.id.raw_value), which returns a data URI if you included the field in your fields list and the field is set, a placeholder if the field is not set, or a URL that makes Odoo stream the field's contents if you didn't include it in your fields list. Do not include the field in the fields list if you need to display a lot of records simultaneously or you expect very big images. Usually, you'd use this in a t-att-src attribute of an img element.