What to do after family members death?

My brother’s wife passed on Friday due to Stage 4 Gastric Cancer.

She has crypto accounts & a Trezor wallet. My brother does have access to all of these accounts.

We live in New Jersey. She had no will. She left behind my brother and 2 small children.

Is he allowed to hold or sell any of said crypto if it’s her account and he is next of kin?

We are just trying to figure out how to handle anything post death, as everything is connected to her social security number with these apps and wallets, I assume.

Is he allowed to sell if he needs money to care for the kids, due to NJ intestacy laws (no will)?

Does all of the crypto die with my sister in law?

Just trying to help him get answers as we are all trying to figure out the things that need to be taken care of to set the kids up for the future.

Thank you for any advice/help.