Wrong fit ? Trauma? Reluctance to grow up? Personality Type? What's the right answer?


Hey everyone, I hope you all are doing good.
My head is a blender right now and I thought I would appreciate people's perceptions of the situation.
I posted once before about my current work environment and received a lot of support.
For context and summary, I had to decided to take a new role at the same work place, it still involved some interaction with the abusive boss, but less than before. The new role is split time between two departments.

Department 1 - Everyone does overtime as routine, I pushback because I really need the time off to regulate. I am feeling like the dead weight on the team, and this is making me feel guilty. I've been trying to protect my therapy time slot (its after work hours) but I am feeling continual pressure to work during it. I am getting great boundary setting practice (silver lining?) and I love the work itself, but the continuous boundary setting is draining me emotionally. I feel the assertiveness this place is teaching me though will really help in the future.

Department 2- I feel a weird sensation at this place, like I have my head in a fish bowl and cant really understand what's happening. No one seems to be working, every one talks about their work load, the junior staff all hate it, say they can't progress here and the higher ups in the department actively sabotage their progress, and there's really not much of a middle tier except for 3-4 people who are like ghosts (you never see them around or talking to people) but they at least seem (?) focused on their actual work and able to move forward. Higher ups everyone says are really horrible have been nice to me so far, but I keep waiting for the other shoe to drop. At this place, I have also gotten in trouble for really bizarre things (not being able to take a surprise meeting from a remote location while I was travelling during my annual leave, the server of another company crashing where we hadn't submitted our stuff a couple of days before deadline, because the project lead hadn't done her stuff, she also yelled at me lol, basically a lot of throwing junior staff under the bus) so I also keep waiting for the other shoe to drop for this reason. I keep being assigned coordination roles by the department head and I cant help wondering if its because he thinks its a good strategy for mentoring me (which he has said he is trying to do, and does send opportunities my way) or because I take on a lot to make sure that the project gets submitted/am an easier person to throw under the bus. I also hate coordination, but have an atuomatic freeze/fawn response 50% of the times I talk to him and I dont feel I can communicate this to him at this point. But I am feeling an internal pressure to stick it out, and that people havent been able to succeed in this place because they are in codependent dynamics with the supervisors, which for some reason I am feeling like I can avoid (yes I know ironic considering what I just said about the department head)

Questions I am struggling with:
1) dept 1- What is everyone's sense for how many times they will communicate boundaries before deciding that the culture is just not a good fit? Is there a possibility to be able to survive there without caving to the coworker pressure?
2) dept 2 - Am I stuck in some form of stockholm syndrome because they seem nice to me now, I think the other shoe wont drop?/feeling like I can change the situation etc.
3) I have the option/opportunity to bail on this whole shebang and start my own small business, which may or may not bring in the same income for a few months/years. I am scared of not making rent/having to shift back into abusive parental household in this situation. Both options expose me to more trauma in one way or the other - how do I decide?

Thanks for reading all of this! <3