The first two Twitch drops on offer are the Legendary Kiriko Sukajan skin and her extra “I take care of my friends!” voice line. In order to get both of these, you’re going to have to watch any Twitch stream in the Overwatch 2 category for six hours between 8 October at 5:00 AM (GMT+8) and 16 October at 2:59 PM (GMT+8). After you watch for two hours you’ll unlock the voice line to claim on Twitch, but then you’ll need to watch a further four hours to get the Sukajan skin.
The second set of Twitch drops includes the Razor Sharp Kiriko spray and the Donut weapon charm. For the first, you’ll have to watch any Overwatch 2 stream for two hours between 18 October at 2:00 AM (GMT+8) and 24 October at 3:00 PM (GMT+8). If you want that Donut Weapon Charm as well, you’ll need to watch for a further three hours, for five total.
It’s worth noting that you don’t need to watch the same channel the entire time to earn your drop, so you can progress towards it by watching multiple streams a bit at a time if you choose.
Once you’ve watched enough to earn the drops, you can claim them in your Twitch Drops inventory page. You can also find a full breakdown on the official Blizzard blog post, including which regions can participate in the drops.