The Simply Piano App that can be downloaded on all technological devices has become very popular amongst in particular younger learners. During lockdowns, all kinds of music learning apps became very popular when face-to-face lessons were not possible.
In my experience, these apps can be a great tool for learning the basics of a musical instrument and for getting the hang of the rudiments of music theory. Simply Piano and other apps can help with forming a solid foundation on which to build with subsequent lessons and learning. What I have found is that using an App alone is not enough for further development, but if one is learning just for fun and the enjoyment of playing the piano, an App can be a sufficient guide. A combination of using an App and taking either online of in-person lessons is the best way forward if one is inclined to use technology. In the end of the day, nothing can really beat live feedback from a teacher!