There's a Cyberpunk 2077 Hideo Kojima cameo and a Death Stranding Easter egg to find if you know where to look. They're easy to completely walk past though and it's a big game so if you want to find them in-game I can explain the missions you need - a main quest called The Heist, and a Detective River Ward side mission for called The Hunt - as well as the where what and when of how to find everything. So here's where to find the Hideo Kojima cameo in Cyberpunk 2077 and the Death Stranding Easter egg.
Cyberpunk 2077 Hideo Kojima cameo location
During The Heist mission you'll check into a hotel with Jackie to prepare for a job. Once you're in the building, follow Jackie until you're given the option to look around or go straight to your room.
It's a timed choice so pick 'Gonna have a look around' quickly, which will open up an optional objective to 'Check out the hotel bar'. Do that, as this is where you'll find Kojima - he's at a table to the back of the room and to the right of the pink bar, talking to a group of people. Here, specifically:
If you walk closer you'll hear him talking about his work - trying to "surpass the expressive limitations of braindances" (Cyberpunk 2077's mind altering version of video games). It's all very Kojima, here's what he says in full:
"Thus far the biggest problem with braindance has been its expressive limitations - the scrolls are too simplistic. Laughter means comedy, horror means fear, and romance means love and passion. It's the same as movies that rely on genre tropes. There is more to capturing emotions than that, which is what my research team in Tokyo is currently working toward achieving. I want my productions to convey real, raw human emotion. For example, the feeling when you combine happiness with melancholy or being calm with an underlying sense of anxiety. These complex, realistic feelings and emotions are what I aspire to recreate… woven into much better stories, of course."
Once he's done talking you'll be able to say hi and discover he's called Oshima in the game, before he asks if you have a pitch for him. You can't do much more than that though, so once you've found him and bothered him a couple of times move on with the mission.
Cyberpunk 2077 Death Stranding Easter egg
The Death Stranding Cyberpunk 2077 Easter egg is nowhere near Kojima and will need you to have completed a side mission called I Fought the Law, where you meet Detective River Ward. Once that mission is out of the way he'll eventually call you back to ask for your help investigating a serial killer that appears to have taken his nephew. As part of this mission, called The Hunt, you'll break into a clinic researching braindances and dreams. Inside, look for a room with two giant white robot arms - between them - in a spotlight is a BB from Death Stranding on a pedestal.
If you head up and scan it you'll see a description that says it's a device that 'simulates the conditions in the uterus' and that its use is to 'maintain the life of the BB and detect BTs'.
Fortunately there aren't any BTs to worry about, unless there's another Easter egg we're yet to find. For now at least, that's all the Kojima related secrets you can find in Cyberpunk 2077.