The intention is that people will be able to get alerts from Samsung when the phone is ready for pre-order.
Samsung's goal for this is likely twofold. It's a way for the company to gather more email addresses for consumers who are interested in its products. But more importantly it's a way for Samsung to gauge the demand of the device early on.
Which is a smart play by Samsung. Because consumers that are willing to reserve a Galaxy Note 20 before pre-orders are available are more likely to buy one. So it'll have a better idea of how many to ship on day one.
Reserve a Samsung Galaxy Note 20 and save some cash
There is some incentive for people to reserve the device. While it does help Samsung gauge demand for the phone, it also allows the consumer to save some money on the purchase.
If you reserve the device then Samsung will give you a credit of $50 on the purchase. There are two things to mention with this. One is that you have to complete the pre-order (probably through the email Samsung sends you when pre-orders go live).
Two is that the credit is instant. So whatever the Galaxy Note 20 costs at retail, those that make a reservation will pay $50 less. If you do plan to buy the phone, that's a nice little perk and probably worth your time.
Reserving does not mean you have to buy
If you put your name down to reserve the phone it does entitle you to that $50 credit. It doesn't mean you have to actually buy though.
So if you change your mind before pre-orders go out then there's no obligation for the purchase. In addition to adding your email Samsung asks consumers to pick the carrier they will be placing the pre-order through.
This can also be changed before the completion of the pre-order. So choosing Verizon at the beginning does not mean you actually have to complete the pre-order through Verizon if you decide you want the phone on a different carrier.
Making a reservation also lets consumers have private access to pre-order. Which means you should have first crack at placing a pre-order before any consumers that did not reserve the phone.
There's no telling how many people will be interested in buying the device. So if you're considering getting one, placing a reservation is recommended to ensure you have the chance to buy.