I found a commit that explains it:
In here the tiny native launcher is updated due to Apple dropping support for building with an older target. This means that the current release requires MacOS 11+ (Big Sur), which matches your findings.
Python was used as a way to get the tray icon up through RUMPS because the ObjC and UI toolkits were hard to work with from C#. As MacOS then dropped Python (plus py2 → py3) this made it problematic.
The current canary builds are using AvaloniaUI, which requires MacOS 10.13 so it should work on 10.14, no additional libraries needed.