Ever wanted to use one of your Teams apps in Outlook? Well, it's something that Microsoft is planning, as the feature was recently added to the Microsoft 365 Roadmap, for release later this year (via Windows Central.)
According to the roadmap entry, Microsoft says that Outlook users will be able to "acquire and use these updated Teams apps," without leaving Outlook. Presumably, this hints that developers might need to update their Teams apps to support both apps. It also looks as though these cross-Teams and Outlook apps are catered for personal, and/or search, per the roadmap.
The feature is set for release in December of 2022 for both Outlook on the web, as well as desktop. However, seeing as though that's just Microsoft's best timing for when you can expect this, it could come even later. Also, with Inspire 2022 coming up in July, you might expect the company to talk more about this then, as the conference always sports a lot of Teams news. Until then, you'll just have to settle with using your Teams apps separate from Outlook.