Inbox in Gmail by Bouke Stam

This extension was made to add some of the useful features from Google Inbox to Gmail. It shows all emails sent to yourself with subject "Reminder" as reminders inside your inbox. It also groups emails by date (today, yesterday, this month, etc). The extension also cleans up the Gmail interface to come closer to the simplicity of Inbox.

This extension works best in English, since it relies on specific date formats.
It doesn't support the dark theme yet, so it only works with the default theme. If you are having problems with white/invisible text or icons, this is probably why.