Best smart calendar without subscription?

Title, but also wondering if a smart calendar exists that has all the features I’m looking for. I’ve done a lot of research but keep getting deterred by reviews or wondering about accuracy when fake reviews exist. I just want to hear from real people who have actually had success with their smart calendars, and any tips/tricks/advice would be greatly appreciated! Features I want: - No subscription (or at least a financially friendly one) - Syncs with multiple calendars (at least two) - Compatible w/ Apple AND Android (I have Apple, my BF has Android) - Alerts/reminders for appointments/todo lists/chores - Color coded calendars for different people TIA! <3