This question boils down to "How do you market something?" Ideally, talk to an experienced marketer who knows the domain. They're going to give you much better advice than randoms on HN (although, HN being what it is, the founder of a successful productivity app company might reply... :) )
More generally, if anyone has an idea for a side project or a startup that they're thinking about at the moment, and they don't have an answer to the question of "What's the route to market for this?" then you should seriously consider answering that before writing a single line of code or designing a single screen. Thousands of amazing startups run out of money and shut down because they couldn't answer this question every year. It's important to figure it out as early as possible. It's the source of all your customers, your feedback from real users, and the life blood of your business - revenue.
Having some marketing experience, I would say that most marketers would not be able to do this. That is, if their experience is working within marketing departments. What you really need is people who have done exactly what OP asks about, and in that role done some tasks that could be classified as marketing. But a lot of marketers have never launched a new tone side project or startup zero to one, so they don't know how to do it.
Modern marketing is unfortunately siloed with a very narrow purview that is not at all close to covering the 4Ps, which is what marketing really should be about.
More generally, if anyone has an idea for a side project or a startup that they're thinking about at the moment, and they don't have an answer to the question of "What's the route to market for this?" then you should seriously consider answering that before writing a single line of code or designing a single screen. Thousands of amazing startups run out of money and shut down because they couldn't answer this question every year. It's important to figure it out as early as possible. It's the source of all your customers, your feedback from real users, and the life blood of your business - revenue.