You can code a contacts manager app. It needs to add, read, edit ans rénové contacts. The more data you can manage the better, for example, work and personal phone numbers and email. Job title, company, created at, updated at, last time read at, etc. For each field you need to manage input sanitation, error handling and error messages. For profile photos you can do picture upload, read image from social network like a proprietary one or from the fediverse.