How do I generate PDF content from a node? We are looking for a way to convert the Drupal pages into PDF on click of a button for D8. Initially we thought we could use Print Module, but that only has a D7 version. 

How do you create a button in D8 so that on click, it will convert the Drupal node into a PDF keeping the current theme styling and elements appropriately? We have been unable to find any D8 modules or process that can allow for this.
You can achieve with several solutions 

Use Entity Print Module


  Entity Print allows you to print any Drupal entity (Drupal 7 and 8) or
  View (Drupal 8 only) to PDF.
  
  The module is lightweight compared to other modules like the Print
  module, has full test coverage and is ready to be used in production
  for both D7 and D8.


Use new host of print module (Printable Module)


  This is the new home of the print module. The module makes use of
  pdf_api module to generate PDFs.


Use PrintFriendly Module (it supports localization very good)


  The #1 Print and PDF button for your Drupal site. Printer Friendly
  pages without coding, css, or print.css. Fast, easy, and professional.
  
  The Print Friendly &amp; PDF button saves paper and ink when printing or
  creating a PDF. It's fast, easy, and looks great when printed. Add the
  button now, and your users will see the difference.
  
  How Print Friendly &amp; PDF Works The Print Friendly &amp; PDF button
  automatically creates printer friendly and PDF versions of your pages
  without the hassle of having to create a print CSS file. No coding,
  hacking or programming required. Simply install the Print Friendly &amp;
  PDF plugin, activate, and choose settings for full customization. It
  also gives your user the ability to remove images and paragraphs of
  text, so they really only have to print exactly what they want.


And final solution is kind of tricky solution, instead of converting the page to PDF just  provide a print theme style for your nodes, when a user clicks on the print button (or link) trigger  javascript:window.print() action. most of the new OS has PDF printer build-in

By the way, I recommend PrintFriendly Module