CD Projekt Red has this whole rewards system thing going on with Cyberpunk 2077: Phantom Liberty. Jumping through a few simple hoops will net you some pretty cool rewards—like a snazzy pistol that sets people on fire—and all it'll cost you is your time.
As outlined on the My Goodies page, registering for the My Rewards system will net you some swag, depending on which games you have installed. Doing so typically shakes down to launching the game on your preferred platform, and then signing into your GOG account via the launcher. You can find specific instructions for each platform on the rewards page.
One reward—a pistol by the name of Scorch—can be snagged for free. Simply download Gwent on GOG (or your linked platform) and you'll be able to claim the gun in-game by travelling to V's stash. You can find it in the stash in their apartment or stash in the trunk of any vehicle they own. Here's a screenshot of its stats:
Fittingly, this side piece has a 20% chance to Burn enemies as well as a solid headshot damage multiplier and some armour penetration. It's also an Iconic weapon, meaning it has a unique modifier: if you hit a charged shot against an enemy that's already on fire, all three bullets will be reloaded back into the magazine, letting you Igni to your heart's content.
From what I've seen, the weapon's tier does seem to correlate with your character's level—the one I found was tier 4, while my colleague has a tier 5 one—so if you're planning on making some endgame build with it, it might make more sense to respec a pre-existing V. If you're having a bit of trouble activating it on Steam like I did, fully downloading and playing a bit of Gwent seemed to fix the problem—and I was later told that downloading and running the games in question is crucial to activating the rewards.
You'll also get a fun Gwent t-shirt with some hilarious lore implications. If Gwent released on the same date in Cyberpunk 2077 as it did in our real world, that'd make it 70 years old. At the very least, that makes this video game swag vintage. If you happen to already own Witcher 3: The Wild Hunt, you'll also be able to get your mitts on Gwynbleidd and a Wild Hunt Jacket.
This iconic sword deals extra damage against bosses, but it's good for slicing through mooks as well. Getting a rapid chain of kills will start guaranteeing critical hits, and you'll also get this benefit if you're just low on HP. Steel for humans, indeed. Do note that this will arrive in your stash when Phantom Liberty releases on September 26, though you can play the game's preem 2.0 update right now.