My Mom's Apple ID was stolen, iPhone erased and locked out of

My mom received a call claiming to be from Apple Support about a suspicious charge to her Apple Card. She fell for the scam and ended up giving the caller the password to her Apple ID and the passcode to her iPhone. The caller then got into her phone remotely, changed her Apple ID password, and switched the trusted phone number to a completely new number. She then got emails that her phone was put into Lost Mode and then another email shortly after that said her phone was being erased. The same thing happened to her Apple Watch. When she turned her phone on everything was reset and she was locked out of her phone. We ended up changing as many important passwords as we could think of that she used on her phone shortly after she had realized she had been scammed.

We have already reached out to Apple Support and were told that she needed proof of purchase of her iPhone and that Apple would review it and are currently waiting for her phone provider to send us a copy of her receipt when she bought the phone.

After what I've already seen online, it looks like she'll lose everything that was on her iPhone before it was compromised. I'm just curious if she'll still be able to use that phone again and will just have to make a new Apple ID account or if she'll have to get a new iPhone and a new phone number. I also don't know if the "hacker" still has access to all of her information and data that was on her iPhone or if it was wiped once they erased her iPhone and Apple Watch.

If anyone has any sort of information regarding any of this please let us know, thank you