Ok, if I have understood correctly the ASICs do not implement the cryptographic algorithms but they directly apply a cryptographic function, is it correct?
Yes. Bitcoin ASICs are only designed to hash SHA256 twice and nothing else. The data is fed from a computer.
And if in any way the ASICs "contain" the SHA256 (regardless if algorithm or function), is this content symmetrical or asymmetrical?
Sorry, I've made a mistake. It is neither.
Asymmetrical and symmetrical are terms that are used with encryption. In Bitcoin, there is neither the encryption or decryption of any information at the protocol level. SHA256 is used for
hashing and not for
encrypting; SHA256 cannot be reversed to get the original text.