Heat the Instant Pot using the "Saute" function.
Add the bacon and cook until the fat starts to be released from the bacon and the edges of the bacon are starting to brown, about 5 minutes.
Add the diced onion and saute until the onion starts to look transulacent in color, about 5 minutes.
Stir in the garlic and saute for 30 seconds or until fragrant.
Deglaze the pan with the chicken stock and stir in the apple cider vinegar, brown sugar, and crushed red pepper flakes.
Turn off the saute button and add the collard greens and ham hock.
Place the Instant Pot lid, lock it, and ensure the steam nozzle is in the “seal” position.
Cook on manual, high heat, for 5 minutes. Once the IP beeps after it has cooked, let it naturally release for 15 minutes, then manually release any remaining steam.
Remove the lid from the Instant Pot, remove the ham hock, cut off any meat, add back to the greens, and gently stir to combine.
Taste and season with kosher salt or black pepper if desired.