In a medium bowl, stir together the Greek yogurt, 3 tablespoons honey, and vanilla extract until smooth and evenly combined. Taste and add more honey if you prefer it sweeter.
Slice the bananas into 1/4-inch rounds. If making ahead, toss gently with 1 teaspoon lemon juice to prevent browning.
Take 4 clear glasses or jars (8-10 ounce capacity). Spoon 3 tablespoons of the honey yogurt mixture into the bottom of each glass, spreading it to the edges.
Layer 4-5 banana slices over the yogurt in each glass, arranging them in a single layer if possible.
Add 2 tablespoons of granola over the bananas, keeping it mostly in the center to prevent sogginess.
Repeat the layering process: another layer of yogurt (about 3 tablespoons), more banana slices, and another layer of granola.
Top each parfait with a final dollop of yogurt, a drizzle of honey, and a sprinkle of sliced almonds and chia seeds if using.
Serve immediately for the crunchiest texture, or cover and refrigerate for up to 24 hours. Add the final granola layer just before serving if making ahead.