I seem to recall there was a hint of a hope that there would be a free ware portion of the marketplace once they clear the pay ware backlog, and theoretically this would allow things like your liveries to be released for Xbox.
It is not technically possible. The Xbox is a closed ecosystem, and DLC can only come from the Marketplace. Even Jorg didn’t realize how closed the Xbox is. He knew things had to come from the Marketplace, but on another front, they were just about to release the new cloud scenery editor (I forget what it’s called, scenery hub or something), and found out from the Xbox gods they had not covered all the bases on how files can be saved or something or other, a bunch more rules they were unaware of. So that delayed the launch of that product for MSFS.
As noted above, however, Jorg is working on a freeware section of the Marketplace. Who knows how it will work, but they are trying hard to do it.
As of SU14 Asobo chose to replace the SR22 with a different 3d model for little benefit. This rendered all existing SR22 liveries useless. As a result this livery is no longer suitable for use with MSFS.