I am not from Laminar Research; just a flight simmer using the official version of X-Plane developed by Laminar Research.
I don't support steam. It is a 3rd party hybrid version of X-Plane taking a commercial advantage of the development work carried out by Laminar. There is no commercial connection between Laminar and steam.
The Laminar Research version of X-Plane and the steam versions cannot be "mixed". You will have to live with steam at this stage.
From previous comments in this forum steam is always behind the "eight ball" or slow in providing updates when the new versions of X-Plane are released by Laminar. They may not even consider making beta versions available.
The official release version of x-plane for normal public use is 11.26 which you have. The official 11.30 public release of x-plane will only be made available when Laminar is satisfied all the "bugs" have been fixed in the beta versions. The update process by Laminar is release a private beta version to selected testers then a public beta testing process release and finally the official version release. When released, the official Laminar version can be downloaded (updated) immediately as you boot-up and run X-Plane Steam eventually makes the update available.
When X-Plane 11 was officially released there had been multiple beta versions made available over a lengthy period before the public release. My reading of comments in this forum at that time strongly suggested Steam did not make beta versions available as X-Plane 10 steam users wanted to test the new version.
As this forum is not a Steam forum and you may not accept my answer then contact Steam directly to ascertain if they make beta versions available. Otherwise, be patient until the official version is released to you by the hybrid developed version of X-Plane.