Yes, as @Seller_ZJhFeE3tNKzfhsaid, if you are registered as an Amazon Handmade seller, you can waive the monthly fee. They will probably take the 1st payment, but you have to message them to get it back and get them to stop future payments. Unless they've improved since I joined (2019) - though unlikely!

Amazon are still saying that we can sell to NI safely even with GPSR. For the moment, I'm just going with the flow and seeing what happens.

I've seen it said that the EU will be looking at individual cases on a case-by-case basis. And there will of course need to be a grace period for all of this. So I highly doubt they will be jumping on small sellers right from the start. Yes, they will have the big marketplaces in their sights, but they also take into account what systems and processes they have put in place, so (like Etsy, who still can't understand the difference between Ireland and N.Ireland despite having a base in Ireland!) you could argue that as you have to sell to the UK and Amazon & Etsy haven't made it so you can strip out NI, then it's not exactly your fault. It might seem a risk too far for some, but I'm happy to sit back and see. I'll have to stop mid December until after NY anyway because of the slow post, so I'm unlikely to get anything from NI.

Oh and there's also some uncertainty (with some experts) about what constitutes a 'new' item placed on the market. Depending on what you sell and when they were made, you could argue the items were pre-Dec13. How would the EU know what you have made and what you haven't, if you've been listing that product for months or years.