You can use Pixel Persona to add photo-realistic textures to your vector designs using pixel brushes. Alternatively, you can use basic hard- and soft-edged pixel brushes to add shadows and highlights to your work.
Affinity Designer provides an impressive selection of pixel brush designs for use with your Paint Brush Tool. Each category contains brushes of varying properties and characteristics.
You can also create your own pixel brushes to assist with your design work. If you want to save a brush, these can be stored in the panel as a custom brush for future use.
By default, if you switch away from a brush tool, when you return to it the last used brush will be remembered (even any modified settings), with the Brushes panel automatically scrolling to the brush; switching across brush categories is automatic. You can switch off auto-scrolling/auto-switching in the Brushes panel's preferences if needed.