Yes, you can create a simple app using your phone, but it may have limitations compared to creating a more complex app on a computer. There are several app development platforms and tools that allow you to create basic mobile apps using your phone. Here are some options:
Keep in mind that creating complex and fully-featured apps typically requires more advanced development tools, which are generally more suited for use on a computer. If you are interested in creating more sophisticated apps, you may eventually need access to a computer and more robust development resources.
Additionally, while creating a basic app on your phone is possible, you may still need to test and deploy the app on an actual device, which might require access to a computer and additional development steps. If you are serious about app development, investing in a computer and familiarizing yourself with coding languages and development environments would be beneficial.