We are due for a 2019 Q2 release of Horizon any day now. This next version will likely include 1903 support and that could extend to 7.8/7.7.
7.8 was release in 2019 Q1 on 3/14
7.7 was release in 2018 Q4 on 12/13
7.6 was released in 2018 Q3 on 9/6
7.5 was released in 2018 Q2 on 5/29
What is VMware’s current Guest OS support policy with Windows 10 releases for Horizon 7.x?
Horizon 7 Server and Agent will support the new Windows 10 Semi Annual Channel (SAC) releases. Microsoft recently changed their Windows 10 policy and each new version of Windows 10 SAC will be declared to be broad deployment ready by Microsoft. Shortly after a new SAC is released, VMware will qualify the new Windows 10 SAC release for the most recently released Horizon 7.x Server and Agent.
At the release of a new Horizon 7.x release, tech preview or GA support for most recent SAC version in the targeted deployment phase will be available. At the release of the new Horizon version, production support for 2 most recently released versions of Windows 10 LTSC and SAC in broad deployment phase will be available.
I did some digging and there appears to be a known issue with Horizon connecting to a physical PC running 1903.