@Artem Volkov If it is small project IaC then PRs is fine (extracting the module and having sensible defaults). If you don’t want to have the overhead of Tickets, give them auto deploy / destroy access limited to their environments. [roles and authorization is the tricky part]
Also unsure whether you need abstraction at helm charts / terraform / application level, depending on that your solution could be simplified. Could you share more context on what each new team would need.
Given that your org’s huge, you could end up building custom wrapper and exposing yaml which simplifies deployment from end user perspective.
We’re building a platform (IDP) for orgs to deal with the similar issue. DM’s open, would love to chat in detail.