As of this moment MSFS has no default VDGS system, as you stated support is 3rd party. Which requires running 3rd party code, which is something that console manufacturers have resisted since the first console. They avoid 3rd party code at all costs purely for security reasons, because they do not want their operating systems to subject to a jail break.
“Jailbreaking is the process of exploiting the flaws of a locked-down electronic device to install software other than what the manufacturer has made available …”, Kaspersky Laboratories
This is why WASM on a console is regarded as groundbreaking, because it allows 3rd party devs to run java scripts in a sandbox.
A sandbox allows 3rd party code to execute while still being isolated from the console O.S.
For performance reasons, historically speaking, console software has always operated very close to the hardware, with little security overhead. So console manufacturers have always maintained final approval for any code that hit the their console. Until Xbox Wasm.