Honestly, unless you don’t already have an established "name" (whether website, enlargement device, or popular & veteran member of a forum), it’s quite challenging to make money that’s worthwhile.
Things that may work that come to mind are:
1. Coaching. But like real Personal Trainers, you have to show your success in quality Before & After’s (whether your own unit, or a Portfolio of other people) to convince anyone to pay you to help them.
2. Scamming (obviously, one I don’t endorse LOL) — like creating pills using a lot of common ingredients found in most penis pills but with your own ratio and quality, and insisting this one is the one that "REALLY WORKS!" It’s likely legal (i.e. described as herbal supplement) so technically not a scam, but most certainly misleading and, yea I just thought it was funny to include, would NOT recommend.
3. Product Invention. I know of one which will be revealed to the market soon that is a huge leap in penis pumping, and like this one, something novel, unique, or highly innovated to capture the attention of those who are not faring well with other devices or exercises.
4. Become a Nurse with training/certification in Injectables, some States will let you perform penis enlargement by using dermal fillers off-label. And if this doesn’t give you the business you hoped (or if you were simply not good at it), you can still fall back on the fact that you are a Nurse which is always in high-demand.
5. Become a statistical anomaly of a success story through PE methods (e.g. freakish gains) and become an OnlyFans model (regardless of your orientation) just to showcase your penis.
That’s all I got.