I have an autolaunched flow to create a record with particular field values, unless a record with the same values already exists. This answer offers a method for interactive flows. This answer says headless flows can do the job, but doesn't explain how.
Get Records successfully finds the record if it exists, but errors out if it doesn't.
equals count
: jenwlee.files.wordpress.com/2018/06/flowcollectionwithcount.gif