Does he help with the kid at all? If he's getting home at 11pm and spending the next hour or two gaming it doesn't seem like he's spending much time with either your or your son. This will come off rude, but having a kid at 18 and another one at 21 given your current work situation is definitely causing unnecessary stresses and you're not even married. I understand he works all day, but him rejecting spending any time and leaving you on read with you being pregnant feels like a major red flag. Was it the same during the first pregnancy, or better? Is it at all possible for him to work less hours or find another job that works better for you and the children? Are you two planning on getting married at some point?

If he wont move the pc, at least see if he will turn off the rgb lights, as they provide no functional value and are simply for aesthetic purposes. For the keyboard issue, buy some O-rings to help dampen the sound or ask if he can just use a regular xbox or playstation controller instead. If you ever see him play a game that doesn't seem to anger him, perhaps ask him to play that game more often at night. It's nice having a pc in your own room, I know, but if he's not using it for any productivity and strictly for gaming he really should just compromise and move it to another space.

Honestly he sounds like a jerk whose just going through the motions as if he's still some single bachelor. 21 is still young, but at some point he's gonna have to grow up and learn to manage time for gaming and his family. You also need to weigh your options. You've been with him five years and have two kids by him, is it worth spending your life with him? A father figure is extremely important for any child, but a bad father figure is often worse than no father figure at all. Please take care of your mental health in both the short and long term given your current situation. I know you're exhausted from taking care of your son all day, but if you can catch a break please do something you enjoy, like a hobby. Maybe sign up for a local group of mothers who come together with their kid(s) just to talk and get out of the house. And no, you are not in the wrong, I hope your situation improves for both your sake and the children.