In a small bowl, whisk the coconut sugar and yeast into the lukewarm oat milk and let stand until foamy, about 5 minutes.
In the bowl of a standing mixer fitted with the paddle, mix the flour with the yeast mixture.
Mix at medium speed until shaggy, about 1 minute, cover the bowl and allow to rest for 30 minutes.
Add the salt to the dough and mix in the eggs one at a time, mixing for 20 seconds between each.
Whisk the coffee with the melted coconut oil, and butter. With the mixer at medium-low, gradually mix in the butter until smooth; the batter will be thick and very sticky. Cover the bowl with plastic wrap and let the batter rise in a warm place until doubled in size, about 1 hour and 45 minutes.
Stir the pearl sugar into the risen batter, allow to rest for 15 minutes. Preheat the waffle iron, gently stir the batter to deflate.
Scoop about 2- 3 tablespoons in the center of the crossing of the iron, close the machine and cook until golden brown and delicious.