Leadership and persistence, there are going to be a lot of ups and downs.
It's easier to do them in a company of others and you'll really need to be persistent to overcome them all 😄
I think you always need some kind of skill to build (code, no-code, design, etc) and some level of marketing or sales (SEO, writing, networking, etc). Depending on the size of your company the second one can be replaced by notoriety/reputation in some smallish community.
Upcoming