Seems like you have a few options
1. Send him to that school and see if his experience is different. It is possible.
2. I know you said you didn't want to homeschool but maybe it would be feasible if you did an online curriculum.
3. Move. I had to do this to get my kids into a better school district and I haven't regretted it for a second.

If teachers are not following your son's IEP you have options to fix that. First, ensure the school principal and staffing specialist are aware, if no help there, go to the ESE department of the school district (they should certainly know the law,) if still no help, go to the state level and file a formal complaint through the Department of Education. Sometimes problems are overlooked because parents don't speak up. The law is on your side in that respect.

Regarding the bullying and related problems schools are supposed to keep our children safe but we all know that you cannot control people/students 100% of the time. Your son's safety and well-being are the most important priority as he cannot learn anything while worried about his safety. You can reach out to the local police department if the school won't address the issues or you can choose to remove your son and yourself from this environment. Best wishes to you both.

I am in Ohio and not in the public school system. But do they still open enroll at schools? maybe an option.

Our district has several schools for kids with special needs as well as charter options. You MUST advocate for your child.

I'm not sure I don't think there is open enrollment to schools here in Florida I will have to check that out.