The aim of this short article is to underline the importance of product managers’ interactions with the engineers in the process of testing feasibility. I cannot claim I know the intricacies of the process, but for sure that the developer is a central piece.
The product team is in charge of the “why?” and the developers of the “how?”. As a product manager it is your job to put the developers in the best possible conditions, so you can both work on answering to the “when?” and the “At what cost?”.
When a product manager thinks about a new feature, it is rather usual and normal to talk to the engineers and test the feasibility of his initiative.
What an engineer will have in mind.
Marty Cagnan is a famous American product manager. In his book “Inspired: How to create tech products customers love”, the author put himself in the position of an engineer and provide a list of general questions an engineer will have in mind. Here are the 10 steps he lists: 
1/ First, the engineer will think about this famous “how?” we talked about: how to build this?
2/ Then, does his/her team has the skills to build this?
3/ Do they have the time to build this? Can they postpone few projects?
4/ Are they going to need any architectural changed to build this?
5/ Do they have all the components they need? Are we already able to do that or do we have to create new components?
6/ What are the dependencies involved in building this?
7/ Will the performance be acceptable? What are the impacts of this new feature on the performance of the app on an old device?
8/ Will it scale to the levels we need?
9/ Do we have the necessary infrastructure? Can we test and run this?
10/ What is the cost? How many people he/she needs on it?
Some of those questions are very techy. We do not expect a product manager to understand all of them. However, I believe it is important that a product manager takes an interest in the “how?”. Same for the engineers, they have to understand and keep in mind the “why?”. (To go further, I invite you to read my former article on product management, “Learning to code, a real asset for product manager”)
It can be rather complicated for an engineer to give a clear answer to all these questions. In some cases, it is rather easy as they have gone through similar processes on many occasions before, but sometimes they need time to investigate.
Give proper time to investigate
When an engineer is not in a position to provide a proper answer, you need to give him some time to think about it. Then he/she will come back to you with an idea of prototype and schedule map for the investigation.
Some product manager will think it is too risky and time-consuming to spend time and money on investigating. I believe it is a big mistake to think in that way. You always have to have in mind that it is the developers who powered innovation. Don’t be afraid to distract them from their coding time. 
“When engineers are given a day or two to investigate, they often come back not only with good answers to the feasibility question but also with better ways to solve the problem” – Marty Cagnan.
Marty Cagnan quote resumes perfectly the situation. It is not time-consuming to include the engineers in the process. Moreover, most of the engineers are waiting for the opportunity to learn a new technology. Make them proud of their work.
To conclude, a product manager who wants to test the feasibility of a new feature will have to be well prepared when he/she will request the cooperation of the engineers. He/she has to be clear on the issue and put the engineers in the best condition to investigate and consider the development of a new product/feature. Asking for a quick and clear answer is the best way to nip a potentially bright product innovation in the bud.
 Marty Cagnan, “Inspired: How to create tech products customers love”, Ed. Wiley, USA, 2018, Chapter 55, p.273.
 Marty Cagnan, “Developer Powered Innovation” – published in the Silicon Valley Product Group insights blog, May 19th 2016.