Heat the oven to 425 °F and line a large rimmed sheet pan with parchment paper.
Halve the delicata squash lengthwise, scoop out the seeds, and slice crosswise into 1/2-inch half-moons. Leave the skin on; it is edible and saves peeling.
In a large bowl, whisk the olive oil, maple syrup, smoked paprika, garlic powder, salt, and pepper. Add the squash, onion, chickpeas, and sausage and toss until everything is evenly coated.
Spread the mixture in a single layer on the sheet pan, leaving a little space between pieces so everything roasts instead of steams.
Roast for 26 to 30 minutes, stirring once halfway through, until the squash is tender and caramelized at the edges and the sausage is browned.
Squeeze the lemon over the pan, scatter with parsley, and serve warm.