Support for custom fields (and/or hooks)

Hello! Do you plan to add support for custom field(s)? Many sites have custom checkout fields and it would be super useful if you could add an option to block users based on custom fields.
It can be something like:
– Enter field id: user_member_card_id
– Enter blacklisted values (one per line): 2021-*
And then add a repeater.
In this example, we want to block the custom field “user_member_card_id” if that field contains a number that starts with “2021-“.

If not, at least give us a hook that we can use in the back end.

Thank you.