Help with FFmpeg feature to convert JPG and PNG to mp4

Hi. It seems there are some cheap hosting companies that come with FFmpeg already installed. I'd like to set up a super simple script that will allow me to upload a jpg or png image and it'll convert it to a 1 or 2 second mp4 file.

Then I'd like a way to get that mp4 file over to my main hosting (VPS). It would be even cooler if there was a way to initiate the process from my main website (on my VPS), but all the magic happens on the cheap FFmpeg hosting.

I'm basically trying to quickly turn jpg and png images into short mp4 videos.

Thanks