Wix wouldn't let me upload an xml sitemap

Wix's automated sitemap generation was not including my pdf files, so I generated my sitemap by having a 3rd party website crawl my site. It picked up the pdf files but I was unable to upload the xml to Wix. XML's are prohibited. I wanted to upload the xml so I could point Google Search Console to it.
However, I found that if I changed the extension on the file to .txt, that I was able to upload it, and Google Search Console was able to parse it as an xml, even with the wrong extension....

Wix wouldn't let me upload an xml sitemap WordPress ...