I would first enquire if this idea can be patented. This could ensure your intellectual property remains with you. This should be your first step, I think. Also, are you able to prototype this yourself?

Here’s a good guide: https://fedecan.ca/en/guide/get-started

There is a DM system, but that’s not really what Lemmy is for. It’s basically a reddit alternative. So blogging in various communities. Find topical communities based on your interests, read what people are posting, comment or post your own.

Follow communities and hashtags to get started