Are Walmart Mopar oil filters good?

i've used plenty of motorcraft, fram and wix here in the uk for decades and had no issues with any. used them on cars, vans and big trucks too.
neil.

Sure, but as you pointed out the UK and EU have their own standards, so even using the same brand and possibly even the same brand and part number between the UK and the US might be comparing parts with different construction. You’d have to be sure that you’re comparing apples to apples, some probably are the same but some might not be.