Inducing hair is only an issue on fine hair. If you’re a male, I doubt you have much of that type of hair on your chest and abs. But regardless, you should only treat patches with dense coarse growth.
Alex is a better laser than a diode, but if your skin can’t handle good settings on it, then you need a diode or a Yag laser.
Diodes are fine, but they’re harder to use. LightSheer requires using compression and not lightly gliding which some clinics tend to do. We’d need to know the spot size, which is either 9mm or 12mm (best) on LightSheer. And you shouldn’t be treated with it unless you can handle at least 25J applied with compression.