Help for California health insurance selection for young Wife with breast cancer.

Hi, I’ve been trying to change my wife’s health insurance from kaiser to 1 where we have the option to access cancer specialists around the country. But it is very confusing. I thought all I needed was a PPO thru Blue Shield, but I can’t confirm what I’m signing up for would work out of state. Trying to go thru the Blue shield website, I put in my zip code and it sends me to Blue Shield of California. Here I’m looking to get the Gold or Platinum PPO. These are the same plans offered on the covered California exchange as far as I can tell. However, when I call the helpline, they tell me I’m only in network for California and can’t access the blue shield in network providers out of the state.
The main place we want access to is Memorial Loan Kettering in New York, who specializes in breast cancer for young women, but ive been unable to confirm if I can get coverage there through the blue shield California ppo plans. All alternatives I’ve tried looked into seem to similarly pigeon hole us in to just California and I’m not able to get the same type of coverage that is offered to employees of companies or government and their blue shield plans that appear to accesa to the blue shield in network across all states.

Can anyone help point me in right direction? We have young kids and just want access to the best places for her disease. Tha ks