You have not provided any example, but depending on the context, "interested product" may not be at all what you intended to say, i.e. "no," you cannot use it as a replacement for "product of interest."
You need to make sure that you understand the distinction between the use of "interested" and "interesting." It may be that "interested" is used in a passive-voice construction, but "interesting" would be the adjectival form. Without an example sentence, it is simply not possible to know whether in your case the substitution to which you refer could be correct.
Meaning: I have interest (in something).
Meaning: You should be interested in me.
- The customer's product of interest was the most expensive one.
Meaning: The customer had interest in the expensive product.
(In this case, "interested product" cannot replace "product of interest.")
- The interested product was the most expensive one.
Meaning: The product in question (being addressed) was the expensive one.
(In this case, "product of interest" could replace "interested product.")
NOTE: The word "interest" can have multiple senses of meaning. Which sense it carries is of significance to this question.
The company wants to understand the customer’s product of interest.
The company wants to understand the customer’s interested product.
Of the two examples now provided in the question, only the first is correct. The second example implies that the product has interest (in something)--which makes no sense (unless the "product" is living, intelligent beings).