In TBD, it's not a "release" until its production ready. The methodology and philosophy doesn't prevent you from developing multiple feature branches at once or even deploying a work in progress feature branch to a dev environment.

All TBD requires in that case is once the feature branch is production ready, it's merged to the trunk. You may need to add a feature toggle if there are multiple release like for different architectures. And you also might benefit from using git tags and deploying to production from a git tag instead of the most recent commit on a branch.

Exactly what you need to do is going to depend on the project's exact needs but TBD is totally possible in that example.