IS IPAD PRO 11 INCH 1ST GENERATION STILL AVAILABLE FOR PURCHASE ON THE WEBSITE?

This version won’t be available directly from Apple “as new”, but may be available from their “reconditioned” stock, for which you’ll find a different page on the Apple website if you search - the location, and availability, will vary by your region or country of residence.

If you are looking for a “new” iPad of an earlier model than is current, try looking an Apple Authorised Reseller - such as Amazon - who routinely carry older models until stocks are exhausted.

no, the ipads listed are the only ipads apple sell https://www.apple.com/ipad/