Generally, a question for the wise. How do people in industry search
for products for reverse engineering if they dont know anything about
If I want to "acquire" the ability to make a product that isn't copyrighted or patented I'd already know what the product does in terms of functionality and performance (else why would I want to "copy" it).
Based on complete knowledge of functionality and performance, I'd redesign the unit and along the way I'd likely improve it. I'd choose components such as the IR device pictured in your question, based on proper design studies and not rely on assumptions that may have been made in the original design that were potentially flawed.
That's how a wise engineer would approach it. If you want to know how a bodger might do it then ask a different question.
In other words, reverse engineering is less optimum at producing a decent solution than a proper redesign (to the skilled and wise engineer).