Pretty much anything that is a substitute for pushups is going to put pressure on your wrists unless you find a way to support the pressure on your forearm above the wrist (not likely). On the knuckles on some kind of padding (yoga mat, carpet) or using dumbbells (like you have been) should help with the range of motion issue.
Freeweight chest presses (dumbbells or barbell) is another alternative for building up tolerance to full weight pushups and beyond.
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