Replace SaaS - Build It Yourself

My wife owns her own business as a tattoo artist. She pays 200 a month for booking software to communicate with her clients, and yet that booking software isn't quite what she'd like. Today AI models like Opus 4.6 are so good that I wanted to see if I could build this app myself for her. If so, I'd be able to replace the 200 a month service that she pays for while also giving her and her clients a truly custom experience.