Moving Outlook 2011 for Mac POP emails to a new MacBook Air M2

This is actually my wife's problem. She got a new 2024 MacBook Air M2 chip, and subscribed to Office 365 for Mac (home and business I think). And is having an impossible time getting her Outlook 2011 for Mac emails to the new computer in their folders. She uses a POP account. She used Apple's Migration Assistant. The individual emails -- all 30,000 of them -- did appear in her new Outlook 365, but without their folders, and the folders are absolutely necessary to organize 30,000 emails.

She's made no progress despite literally hours on the phone with Microsoft tech support -- I'm talking phone calls and chats lasting 2-6 hours at a time, at least 4 times in the last 10 days. Some of the techs seem not all that well-trained, and when they're speaking such heavily accented English it makes it all the more difficult. The tech she's currently talking to sent her a test email to the new computer and it never showed up. It's really stressful since the emails contain her personal and business dating back 15+ years.

So I'm wondering -- can she somehow copy these emails in their folders to an external drive, then import them into the new computer? If the folders don't make the transition, she could copy one folder at a time (we're talking at least 100 folders), import those emails into a newly created folder with the same name on the new computer. So far she's being told that POP emails can't be copied/saved/moved this way.

Alternatively, could she move the Outlook emails to a new Apple Mail account (POP, not IMAP) in the new computer? She wants to keep it POP instead of IMAP because she's been told more than once, including by her ISP, that converting to IMAP will erase all her emails, and she cannot allow that. Thanks.