How-to Limit download format to PDF/A ? [self hosted]

For secure online collaboration, I am looking for a way to limit the download format of files to PDF/A only. People can work on all files online, but when they download a file, they are limited to PDF/A.
Is this possible?

Hello @Wilfried
Unfortunately this is impossible at the moment. But we like your idea. We need some time to discuss such feature internally. I cannot provide you with any guarantees of release of such feature at the moment.