Earlier quoted context omitted.
If you use GSuite Legacy for personal email, you would have the choice of switching to a paid plan, or migrating your email to a personal account (or any other email hosting provider.) If you use a personal GMail account, there is no change here that applies to you.
> migrating your email to a personal account I use GSuite Legacy for a personal email only. So migrating my foo@customdomain.com to a @gmail.com is fine. However, I didn't see anything in the article that indicates that this will be offered or even possible. Where did you see this?
If you use Google's tedious Takeout service, you can get a big zip file which will contain an .mbox file with all of your email. But note, labels don't really apply here, so it'll be one giant folder with all of your email. (That was my experience trying to use ImportExportNG, an add-on for Thunderbird.)
You can also use an application like Thunderbird. Connect via IMAP to your GSuite Legacy account. Connect via IMAP to another account; can be Gmail or another provider. Drap and drop folders and/or individual emails between the two. Works surprisingly well, albeit not particularly fast. I copied about 100,000 emails yesterday evening. The nice thing about this preserving labels/folders.
There are tools in some email providers that would let you login to your GSuite Legacy account and import/copy all email.