I certainly discussed the issue on this forum: Microsoft Outlook 2FA with K9
In short, there’s no way to configure K9 to be compatible with a business e-mail account on outlook.com, because business e-mail accounts don’t support app passwords. We need to have the same Oauth2 support that desktop Thunderbird mail server provides. I still run Thunderbird on my desktop, but for phone access to my e-mail, Outlook is the only available option.
And, despite my preference for POP, I did try the IMAP instructions, which result in a popup saying my provider is not supported.