@danny digital - mailwizz has this super powerful option where it allows you to change a custom field value when someone clicks a certain like or opens your email. Beside the fact it allows you to enter constant values, it also allows you to add tags which later are parsed into proper values, i.e:
Unfortunately this only applies for campaigns from now on.
What you can do, is to go to your list fields and when you click inside the default value field, you will see some tags you can use, such as:
[SUBSCRIBER_GEO_CITY], etc, which you can use as default values, then save your list fields.
Next, go to backend > settings > cron > Custom fields sync, and set it to yes. Then give it a few hours for mailwizz to run and populate your subscribers with the default values of those tags.