Make the guacamole: scoop the avocado flesh (6 ounces) into a small bowl. Add 1 tablespoon lime juice and kosher salt to taste. Mash with a fork, pastry cutter, or potato masher until blended and no longer chunky. Taste and add more lime juice if needed.
Prep the skillet and vegetables: heat 1 tablespoon extra-virgin olive oil in a large skillet over medium heat until shimmering.
Cook the peppers and onion: add the sliced bell peppers and the 1/2 medium white onion to the skillet along with 1 teaspoon ground cumin, 1/2 teaspoon chili powder, a pinch of red pepper flakes, and kosher salt to taste. Toss to combine, cover the pan, and cook, stirring occasionally, until the vegetables are easily pierced with a fork, about 5 to 8 minutes.
Char the edges: uncover and continue cooking, stirring often, until the vegetables develop light char on the edges, about 3 to 5 minutes more.
Finish the vegetables: add the 2 pressed or minced garlic cloves, toss, and cook for 1 minute. Remove the skillet from the heat, drizzle in 2 teaspoons fresh lime juice, toss to combine, adjust salt to taste, then cover the pan to keep the vegetables warm.
Warm the tortillas: heat a small skillet over medium heat. Lightly spray the skillet with olive oil spray. Warm each corn tortilla one at a time, flipping once, until heated through and pliable (about 20–30 seconds per side). Stack the warmed tortillas on a plate and cover with a kitchen towel to keep warm.
Prepare the skillet for eggs: wipe the small skillet clean or use a fresh skillet. Place it over medium-low heat and lightly spray with olive oil spray.
Cook the eggs: carefully crack one large egg into the skillet without breaking the yolk. Cover the skillet and cook until the whites are set, about 2 minutes, longer if you prefer firmer yolks. Transfer the cooked egg to a plate and repeat with the remaining 5 eggs.
Assemble the fajitas: spread a portion of the guacamole on each warmed tortilla. Top each with one cooked egg and a portion of the warm pepper-and-onion mixture.
Finish and serve: sprinkle each assembled fajita with 1 ounce crumbled feta or queso fresco, a handful of chopped fresh cilantro, and freshly ground black pepper to taste. Serve with hot sauce and/or your favorite salsa on the side.