They are my favourite breed too

That’s why I keep all polish except for 2 ex commercial hens.
I’m sure no one is an “expert” as you call it and I’m also pretty sure all the other polish breeders will give you the same answer about your chicks being too young to sex yet.
I’ve hatched hundreds of polish chicks, kept 2 breeding flocks but I am certainly no expert and don’t profess to be either. Just trying to pass on some of my experience, only you can decide to get rid of your chicks if you wish and it shouldn’t be based on what someone else told you to do. Those are your chicks and only you can make that decision.