Hi @thirdspace1. That's awesome that you're looking into curbside!
There's unfortunately not a way to prevent customers from using their gift cards in the online store unless you completely disable gift cards altogether in your online Dashboard.
If you want customers to keep purchasing egift cards through your Online Store and don't want them to be able to redeem them for their curbside pickup orders, you can put some sort of blurb on your website about how you're not currently accepting egift cards as payments for curbside and they can only be used in store only. That might help with slow the traffic for those trying to redeem their egift cards during curbside.
I hope this can work for you. Let us know if you have other questions in the mean time!
