Need to get into locked out Gmail or contact Gmail support

It feels like it would be easier to hack the nuclear launch codes than this. My mom is not tech savvy AT ALL so I have to help her every few weeks with phone stuff. She recently switched carriers and long story short had to get a new phone number.

Every app or anything at all she tries to open or log into, it won't let her because since it's a new unrecognized device it tries to text or call her old, now non-working, number. Of course many also offer the option to simply email but Gmail is like a maze of unhelpfulness. When we try to login to her gmail, we use the corret name and password but it says to verify her they have to text her old number. Obviosly that doesn't work. There's a button that says "I don't have my phone" but when we click that it just dead ends and says "we can't help you now, try again". A google search on account recovery keeps talking about answering questions thoroughly but we've never been asked any questions. I've searched fo ra phone number to talk to a human but apparently Google does not have any support for accoutn recovery or email help.

SURELY there is a way to get into your Gmail account after switching phone numbers right? I mean she can't be the only one that has gone through this. Does anyone have any guidance on how to navigate around this? I created her a new Gmail account just to try to help with this but without being able to get into her old one none of her apps are workable.