Positron isn't supposed to be a replacement for RStudio for all use cases (especially not this early in its lifecycle!). If you open your package folder in Positron (as opposed to the Rproj file itself) I think you'll find it has most of the commands you need for package development in the Palette.

We do hope to add better GUI tooling for project-level actions; more info here: https://github.com/posit-dev/positron/issues/1486