It's one thing to push a crazy amount of power to a device, it's entirely another to do it safely. Thankfully for those of you planning to get a Galaxy S20, the USB-IF has just rubber-stamped the whole Galaxy S20 series as "Fast Charger Certified." When plugged into similarly certified USB accessories and chargers, you can rest a little bit easier knowing that all those watts it's sucking down won't go terribly wrong.
In the dark, distant days of the mid-2010s, USB Type-C charging accessories were a brave new (unregulated) world, and bad cables and chargers could lead to fried ports or devices. For a while, we had the help of Google's Benson Leung to guide our purchasing decisions a bit more safely, then the consortium behind the USB standard itself stepped up with its own certification program for chargers. Today, the consortium is making its first-ever certification of a phone.
Technically, it does matter that every device in the power chain does its job. While a lot can go wrong with a charger (the device supplying your phone with potentially large quantities of power), it's also possible your phone could do something derpy if the manufacturer didn't meet the (terribly long and complicated) USB Power Delivery specification correctly.
The biggest boon of this change is verified PPS support. (PPS, or programmable power supply, is a standard introduced in the Power Delivery 3.0 spec that grants more dynamic voltage levels, rather than fixed PDOs, allowing the flexibility for more efficient charging and thermal management.) We've tested a handful of different devices that claim to have PPS support here at Android Police, and to date, not a single one of them has performed within spec or to the rates advertised.
This new Fast Charger Certified rating means that the Galaxy S20 met the strictest interpretation of the Power Delivery 3.0 spec, and should support fast-charging standards like PPS without any issue. Of course, the numbers supported by each device still vary. The Galaxy S20 and S20+ can pull up to 25W, while the S20 Ultra can allegedly hit up to 45W (though the Note10+, which also claimed that number, never actually did in testing).
Now you'll just have to track down a similarly approved charger — most IF-certified chargers don't do PPS (yet).