Making an app for iPhone is a challenging task given the high standards of the App Store. Developers must ensure good design and excellent functionality. Everything should be optimized to provide the best user experience.
Get inspiration from the most popular apps in your niche. Whatever you are aiming to create, someone has probably already made something similar. Study their implementation and think of ways that you can make things better. You could make the controls more intuitive or add advanced features.
Read the latest design guides so that you can keep in step with the trends and meet user expectations. Try out different tools as well. Several no-code and low-code app builders have emerged over the last few years to fast-track app development and reduce complexity. These might prove helpful in getting projects off the ground despite the lack of funding.