Could be perfect – Calendars 5 by Readdle Review

One critical issue - unlike the build it iOS calendar, the watch complication does not update unless you open the calendar on your phone first. So if you are relying on your watch to maintain your schedule, and someone sends you a meeting invite or changes the start time of an existing meeting, you’re not going to see it reflected on the complication. Had to revert back to iOS calendar.
Review by Ano-nym-ous on Calendars 5 by Readdle.