Toss the strawberries with sugar and lemon juice. Air fry at 350°F for 6–8 minutes, until softened and syrupy. Set aside.
Cut each croissant in half lengthwise to make 8 halves.
In a shallow bowl, whisk the eggs, milk, sugar, vanilla, cinnamon, and salt until smooth.
Dip each croissant half cut-side down for 5 seconds, flip for 3 seconds, and let excess drip off. Do not soak.
Preheat the air fryer to 350°F for 3 minutes. Grease the basket with butter.
Arrange the halves cut-side up in a single layer without overlapping. Cook 4–5 minutes.
Flip gently and cook another 3–4 minutes, until deep golden and crisp.
Serve hot, topped with roasted strawberries, whipped cream, and maple syrup.