You can roll your own. Here's a link to the images:
https://github.com/cyoung/stratux/releases
And here's the page with the incremental updates:
https://github.com/cyoung/stratux/releases
So for instance, to get to the latest bleeding edge release, you would download/unzip/image the latest full image from the first link and verify it works. Then, download an incremental update from the second link. Using the update function that's part of the stratux web page at 192.168.10.1, you can select the incremental file you just downloaded to update the full image to the absolute latest. Be aware though, this puts you on the bleeding edge of Stratux development and you're running the same version that is being tested and tweaked. So some pilots may choose to stay a version or two behind (a "stable" version) unless they are having issues themselves.
There are other ways and links to accomplish the same thing; this is how I choose to do it.