I graduated with a bachelors in computer science around 4 years ago. Long story short, I was depressed, dysphoric, and suicidal throughout my college years and by the time I finished I didn’t want to do anything. I’ve been unemployed for the last 4 years but I’ve also transitioned, started taking better care of myself, and overall I feel much better.
Anyways, I need to get a job now. What kind of lies can I get away with on my resume to cover up the long period of unemployment? Should I pretend I started some sort of company and it failed? Pretend like I went on some backpacking journey in a foreign country? Do companies even check all this stuff?
I did do an internship at a big tech company several years ago, and I’m working on personal software projects so I can put that on my resume. Also, I’m in Amerikkka.
Sorry if this question has been asked here before 
You worked on a backend development of a software as a freelancer but you cannot say more about it, you are bound by NDA.
that's really not how NDAs work
It absolutely can be. The scope of an NDA tends to be about just the details of certain work, but it can absolutely include broad details and basic facts. I suspect it can even include a period of employment altogether.
I know a statistician whose NDA won't let him say which sports team he does analysis for, but for some reason he sure does have a lot of X hats even though he's a fan of Team Y.