If you plan to give up a corporate job, you should go all-in on software projects, since your main advantage is that you can devote 100% for focused development.
1) The hardest tech possible. I want to test my intellectual limits, which was not possible in the corp world.
2) The most hyped areas, today those are AI/Kubernetes.
If you have a unique solution, then it should not be a problem to get early adopters.
Moreover, after leaving my corporate job, I began:
1) Working 17 hours days, 7 days a week.
2) 100% software dev.
To sum up, if you leave the corp, you must increase your focus.
Many of these are more likely to occur when working at a big Corp, so working by yourself can help you avoid this.
The other option is to raise money, but then you switch from a developer to manager.
When you are working for yourself, there is a "no man land" period, where you are trying to switch the economics from selling your time, to selling the product. So you want to work as hard as possible.
Can I ask what you’re building? It is very hard to be productive that long, hence the question
However, you must start dev before the area is hyped and hit the market at the right time.
Also, you must target areas where the big players cannot and will not compete (for example, multi cloud, edge , privacy).