For many years I've used Todoist for managing my task list, both at home and at work. At work I use Outlook for emails, and I wanted to integrate Todoist with the Outlook calendar. I also wanted to view the calendar in a sidebar while the main Outlook view is showing me emails. This is the process which enables all of this:

1. In Todoist, open the project, click the 3 dots, select "Project Calendar Feed".

2. Copy the link labelled "Subscribe with Google Calendar". Ignore the download for Outlook.

3. In New Outlook, go to Calendar and Add Calendar.

4. Select "Subscribe from Web" and paste the link. Fill in the calendar name and other details, then Save and close the popup.

5. The icons at the top right of New Outlook include one which looks like a calendar with a tick. Click that to open the sidebar, and select the Calendar tab at the top.

6. Click the 3 dots next to the month to see a list of calendars.

7. Click "Show All" and select your Todoist calendar.

You can now be viewing your emails, but have a side panel showing your upcoming events, and any scheduled Todoist tasks within that.

New Outlook does have a limitation which means it doesn't refresh the calendar very often. I suspect it only refreshes once per day, though I've not confirmed this. In Old Outlook you could force a refresh by clicking the Send/Receive All Folders button (or the F9 shortcut), but New Outlook doesn't have this functionality.