Someone has looked into setting up an online store for merchandise. Currently
fangamer has a D:OS 2 t-shirt, hoodie, pin and vinyl record soundtrack. Besides that, and
the dice, I don't think there is anything else available.
There have been t-shirts, lanyards and buttons available at various conventions.
Both Kickstarters had physical rewards, and the extra 1k Collector's Edition boxes from the second sold out in just under a day.
There was a retail release of the Divinity Anthology (
contents).
With the original release of Divinity 2 Ego Draconis, a German site had t-shirts and mugs available.
For Beyond Divinity there was a 'fan pack' released of a printed novella (included in the game files as a pdf, covering the story between DD and BD) and a soundtrack CD. The initial UK release of the game also included the printed novella.
I don't recall anything for Divine Divinity, other than the retail release.
There have been several special / collector's editions of the retail releases of games in specific regions.