To make the lightened hollandaise, whisk the egg yolk, Greek yogurt, lemon juice, and Dijon mustard in a small heat-proof bowl until smooth.
Place the bowl over a small pot of simmering water (double boiler method), whisking constantly until the sauce thickens; stir in the ghee, sea salt, and black pepper, then remove from heat and cover to keep warm.
Fill a medium saucepan with water and the white vinegar, bringing it to a gentle simmer over medium heat.
Crack each of the 2 large eggs into a small ramekin, create a gentle whirlpool in the simmering water, and carefully drop the eggs in to poach for 3 minutes until the whites are set but yolks remain runny.
While the eggs poach, toast the split English muffin halves and lightly sear the Canadian bacon in a dry skillet over medium-high heat until warmed through.
Place the toasted muffin halves on a plate, top each with 2 ounces of Canadian bacon and one poached egg.
Drizzle the warm hollandaise sauce over the eggs and garnish with freshly chopped chives before serving.