Connect apps with OAuth2

I am newbie in building Atlassian apps. I am currently building a connect app on confluence cloud. The app will be integrating with a third party application like Slack. I would have to map Atlassian users to their user profiles on Slack. The app will basically notify users on slack of events in Atlassian.
I was thinking the best way to do this will be through OAuth 2.0. But as far as I can tell, connect apps cannot have oauth as well. Is that a right assumption?
In that case do I have to have one connect app and one oauth app? Or do I just use one oauth app instead of a connect app? If I use an ouath app, can I list and sell it on the marketplace ?

Correct, Forge & Connect are separate from OAuth 2 3LO. In fact, using both creates considerable complexity in “wiring up” all the identities across Slack and 2 Atlassian apps. I wouldn’t recommend this solution.

Certainly possible. Do you anticipate any UI inside of Atlassian? If not, then an OAuth app alone could work.

You can list but you cannot sell it on Marketplace. That might be reason to go for Forge or Connect. Both have a sufficient understanding of “user context” that any mapping you do using OAuth, could be done via Forge or Connect. However, I think it is fair to say that kind of user mapping is easier with OAuth. The other frameworks will require some clever use of redirects and custom UI.

It might be worth it to “prototype” your app using OAuth 2 before you switch to an app framework for Marketplace. There may be deeper constraints in things like which webhook events are available. As such, maybe it broad exploration before learning a specific app framework would help.

I do not anticipate any kind of UI inside Atlassian. Is there any documentation I can look at that demonstrates how to accomplish ‘user mappings’ with redirects or custom ui with a connect app ? @ibuchanan

No. So you might be faced with an extreme choice between a lot of exploration and discovery using Connect & Forge for user mapping so that you can sell later on. Or using the well-understood OAuth 2.0 without the ability to sell on Marketplace.