Patent Pending in Different Country

I have created a product that is very similar to a product that was originally designed and marketed in the UK. From my research I can see they filed for a patent in fall of 2019 and it's still pending but it appears to only be for Great Britain. I have found no patent pending or patent requests for the United States. My question is can I sell the very similar product in the US without consequences, both short term and long term? I don't plan on trying to patent since from my research it looks like it would be very difficult to get the actual patent approved. It's not unique enough. The idea is already out there just different designs of it. That said, could this UK company come to the US, file a patent, and effectively close me up? Even if my business is launched and I'm selling in the US? Second question is does a patent have to be approved to carry full weight or is pending status enough? Thank you for your feedback.