"Growth hacking" has been a trendy term in the world of startups. However, hardware founders beware. Your path is inherently different from the software startups.
A software customer acquired with a certain cost ($CAC) for a software startup has a potential to generate long-term revenue stream, depending on retention rates.
A hardware startup does not have "retention" metrics by default. A new transaction with the same customer would not happen until they come back for either repeated purchase or new products.
Therefore, a hardware startup that applies blindly the software growth hacking techniques might end up getting the customers that never return for repeated purchase or new products, much like discount stores only attract consumers going after the cheapest prices, not for the brands.
Especially if a hardware product does not have an inherent network effect, then each customer acquisition is but a CLV (Customer Lifetime Value) equation. They might have been acquired via growth hacking techniques or tools but there's no growth cycle the exponential coefficient of which you could count on.
This kind of growth hacking has absolutely no component of marketing in it. It's not evil by itself but the founders have to take notes that once the growth hacking stops, the revenue could drop back to the level prior to the hacking simply because the whole process has had no marketing effect whatsoever.