While on your iOS device, install this workflow. Then make sure you have Workflow enabled as a share extension in Safari. When you are on a web page, click on the share icon, choose "Run Workflow," then tap on "opml." Then go to Workflowy, and just hit paste (in my testing, even if the cursor is at the end of a line, a new node will be created).
This workflow uses find/replace to convert the characters ?<>" to xhtml entities so that the title won't break if it contains any of them. You can use this page as a test. If you run into any edge cases that don't work with the workflow as it is written, please share in the comments section.