In principle this looks correct, assuming the Viewpixx is really set as the “RandR primary output”, and whatever you set in some display settings GUI does not mean something else: If both outputs have same resolution, the Viewpixx output must be set as primary, e.g., xrandr in a terminal should label it as “primary”, or you could execute, e.g., xrandr --output DisplayPort-0 --primary if DisplayPort-0 would be the name of the output where the Viewpixx is connected.
If the console monitor has a lower resolution than the Viewpixx it should also work - the “primary output” just acts as a tie-breaker in case of identical resolution.
Unfortunately the lack of funding by our users made it not feasible at the time to invest more of my work time to implement finer grained control about this stuff in the X-Server. I barely managed to add this AsyncFlipSecondaries improvement in time for Ubuntu 22.04 / X-Server 21… All the nice things we could have if our users supported us more financially…
-mario