I want to share a url something like:

https://ci.jenkins.io/pipeline-syntax/#expr=retry(2) 

With the result being that:

https://ci.jenkins.io/pipeline-syntax/ loads w/ Sample Step set to retry and Retry Count set to 2.

I'm flexible about the precise syntax

Second example:

https://ci.jenkins.io/pipeline-syntax/#expr=readJSON(file:'x',text:'y')

With the result being that:

https://ci.jenkins.io/pipeline-syntax/ loads w/ Sample Step set to readJSON, File set to x, and FText set to y.

And part two of this:

Next to the Generate Pipeline Script button there should be a Share this script button, it could be a link-symbol or a share-icon.