Question re Greeting cards idea

Hi all. I'm a LONG time lurker in here, have a question for those of you who sell via Amazon.

I'm in the very early stages of an idea/research, but I feel like I've spotted what I consider to be a potential opportunity in the greeting cards market.

I know that many people sell greeting cards via Amazon so the proof is kinda there, but I was wondering if this is the most optimal way of selling these cards, versus something like Shopify?

I'm somebody who would potentially like to venture into private label in the future so this could potentially be a kind of gateway to give me some sort of exposure/experience but obviously with the product likely being ordered online rather than shipped via freight, but I was wondering if people with experience would suggest that this would be a good way of selling via Amazon FBA?