You cannot migrate followers; the only thing you can do is to say what your new user is, and hope that they will follow the new user.

As well, you cannot migrate your own posts; they have an identifier that is an URL that contains the host name of your current instance.

What you can migrate is the people you follow; there is an export function in Mastodon that allows you to download them as a .csv file. You can import them from the command line; the process is documented in the administrator manual, snac(8). You can read these documentation online from https://comam.es/snac-doc .

Anyway, I recommend to just try it first and see if it meets your needs, and then worry about migration.