Hi @art,
Unfortunately, no short term nor mid term plans of spacedesk Driver/Server for Linux.
Protocol specification is not publicly available.
You can only use your Linux machine as client via spacedesk HTML5 VIEWER http://viewer.spacedesk.net/.
Keep in mind that this HTML5 VIEWER app on Linux is much slower than our native apps on Android and Windows.
This is due to technical limitations of HTML5/Javascript.