If you have DX12 enabled without the registry adjustment to Foveated Rendering mentioned way above, it will crash to desktop immediately. If that is in fact the issue, if you either flip to DX11 in MSFS or employ the workaround, it will launch. I had the same thing when testing DX12 with the SU10 beta.
Post 2407 or thereabouts in this thread is where you will find a link to this