I have been writing NSF proposals at NYU for many many years. And always before, there was a mysterious process at the end where we convert our document to Microsoft Word.
Then we hand it over to the powers that be, who turn that Word file into a PDF, and then upload it to a government website, which has lots of rules for formatting. It generally takes days of back and forth, tweaking the document each time, before the website says we have uploaded a valid proposal.
This year we have a new administrative person. She pointed me to the government webpage, and let me try my hand at uploading it myself. So I saved my Google Doc file as a PDF, and uploaded the result.
It all worked perfectly the very first time, to general amazement. Sometimes the simplest thing is the best thing.