Is it possible to create a review without using svn/git Looking to leverage the approval flow without having to create a repository
A differential revision is created from a diff. You will need to have a diff submitted first from which you can create a revision for review.
It is possible to sumit a raw diff by calling arc diff --raw and piping the diff to it.
One example git diff | arc diff --raw will create a diff in phabricator that you can then create a revision from.
So - If you aren't using git you need a way to send in the code diff to arc diff --raw