Some of the Google Inbox people did rebuild Inbox as “Shortwave” https://www.shortwave.com/blog/introducing-shortwave/
Which is available as both an iOS app and PWA. For those unaware, Outlook is also becoming a PWA.
I just wish the IMAP standard would expand to include contacts and calendar.
As of right now, it’s still there and still showing in Hot
https://www.reddit.com/r/ChoosingBeggars/comments/14t18ee/a_website_demands_that_its_voluntary_workers/