As far as I can tell, Foxit has only three Android apps: Foxit PDF reader and Foxit Business PDF reader and Foxit PDF Camera. The first two are reading PDFs.
I might be missing something, but according to their description in Google play, neither of them can create a PDF.
The only app that can create a PDF is Foxit PDF Camera, but it only creates PDFs from the images (taken with the camera, I assume).
I don't know which Foxit you are using, but if it is one of these three, why would you expect this app to accept a text or html and to do something with it?
I don't know much about OfficeSuite Pro (I assume you are talking about "OfficeSuite Pro + PDF", right?), but according to its description on Google Play: "OfficeSuite lets you easily view, edit, and create Word, Excel, and PowerPoint documents, convert to PDF, ..."
From this description, it does not say that you can use it as a "printer to PDF". Maybe it can, but the way I read it, it can save into PDF from the Office format files. It may or may not be able to accept text.
There are a bunch of "PDF creator"s available on Google Play. Some create PDFs from images taken with the camera. None of those that I've tried would work on a plain text. So, you'd need those that are specifically designed to work as a "PDF printer".
I can say that from the message view, 3-dot -> Copy/Send/Share/Print -> Send/Share/Print message text offers me an option to send the message to a few text editors that I have installed (Jota, "Note Everything, ...") and to "Convert to PDF" (from Adobe Reader, which offer me to buy/pay for that).
So, maybe OfficeSuite Pro, if it has a text editor, would work too (but would require a few clicks within it to save the message from the editor to a PDF).