I think those projects are too large of scope. As a solo dev or even having multiple people it would be months and months of programming while having no product and making no income.
And after it’s made you have to sell it, and in these verticals you are competing with companies with hundreds, thousands of employees and millions of dollars investment. This isn’t to say it can’t be done but you are in such a weak position trying to go these routes, in my opinion.
Instead I think you should focus on a SMALL project. Solving a problem for a small group. Something that you could sell the idea of to them before you even began programming it. I.E. creating a solution that they need, that makes their business run smoother. Something you could program in a week. Because the hardest part about a project often times isn’t the engineering, it’s getting people to see it and getting them to pay up.