Preheat the grill to medium-high (about 400°F). If using a charcoal grill, light it and let the coals heat for about 20 minutes.
Cut the salmon into roughly 1/2-inch cubes (the CSV also mentions 1.5–2 inch; use 1/2-inch for consistent kabob pieces). Pat dry with paper towels.
In a mixing bowl, combine the salmon cubes with avocado oil, garlic powder, sea salt, and black pepper; toss gently to coat evenly.
Thread salmon cubes and lemon slices onto metal or soaked wooden skewers, leaving a little space between pieces for even cooking.
Place skewers on the preheated grill and cook until grill marks form, about 2 minutes. Flip and cook another 2 minutes, then flip again and continue grilling until salmon is opaque and cooked through, about 1–4 more minutes (8 minutes total).
Check doneness with a meat thermometer inserted into the largest piece; the internal temperature should read 145°F when fully cooked.
Remove skewers from the grill and drizzle or serve with pesto sauce.