No, you must not charge a different brand's 20v battery with your DeWalt charger, even if it looks like it fits.
Doing this is dangerous and creates a serious risk of fire, electric shock, or electrocution.
The charger is specifically designed only for DeWalt rechargeable battery packs. Using it with another brand can cause the other battery to overheat and burst, leading to injury or property damage.
Even if the physical connection seems correct, the required electrical communication and charging profile are different. A charger designed for one type of battery pack can be dangerous for another.
You must only use the charger specified by the manufacturer for any battery pack. Keep your DeWalt charger and batteries as a dedicated system.