See T7148. Historically, the biggest issue with having an "Export" button on instances has been a policy issue (how do we prevent abuse, like rogue employees using data export as a policy bypass?) rather than a technical issue. The policy issue can be sidestepped by making "Export" a staff action associated with support tickets. So the flow would go:

• Instance files a support ticket requesting an export.
• I click a button that does the export.

All the individual export steps can already be automated as daemon actions, I believe.

This isn't really any less abusable since I have no real clue if someone requesting an export is a rogue employee or not, but it would at least be likely to catch outright nonsense.