Calendar and tasks sync between devices

Ever since I started degoogling my life, i missed how to integrate calendar and tasks in all my devices. Because of my work Im stuck using Macos and I have a debloated samsung device with F-droid. However I need a way of syncing calendars and tasks between Macos and my phone, so I can get push notifications on both of my devices about events and pending tasks, I really need this as i often struggle with ADHD and the only way of getting my tasks done is being very structured with my apps notifying me with the tasks i need to do. Do you guys know what is the best way to implement this using FOSS software?