Adding GDPR Column to admin side

Not sure if this is the best place to ask, but I added my own checkmark for GDPR to comments and easily added to save to the comment meta database and show this on my admin panel with date and time gdpr was accepted.

I would like to do the same with this plugin, but have no idea what hooks are available to make it work. I was able to add a checkmark to the subscriber form and a column to the admin panel, but nothing saves to the database, thus the admin panel gdpr column is empty for date gdpr accepted.

I do currently use the recommended GDPR plugin, but want to remove plugins as possible. This plugin is not actually saving anything to the database either that I can see so it is only assuming the checkmark is working as expected rather than being “compliant”.