I suggest that you contact the city electrical inspector and ask them. I would think that you have the GFCI covered, although not as convenient.

Contractors are not lawyers. So they are not always as up to date as they could be. Lawyers are also not inspectors who may or may not be up to date, but they are the ones saying yea or nay

I looked at NEC 210.52(C)(2) and NEC 210.52(C)(3) for year 2020 and the word "duplex" is not used. Rather, the phrase "at least one receptacle" is used. However section 210.52(C)(3) of the 2023 code states that a receptacle cannot be placed below the countertop like is shown in one of the photos of the Sillites webpage you linked. At $26 each, I don't see that a pair of these is an improvement over a conventional, duplex receptacle.

-- amateur