I have been close to the Venezuela / Guyana border several times. What people are missing is that there is no transport infrastructure whatsoever in that part of the world. This is dense rain forest. People travel by river boat. An army would just get swallowed and spat out.
Secondly, the Venezuelan military may look strong on paper but most of the equipment is unserviceable, training is poor and the army is not in any form of condition to invade anywhere. In particular, Russian jets don't respond well to tropical humidity.
The whole thing is just Maduro playing election games.
The great majority of remaining Venezuelans are just happy to find basic services and food. It's also worth remembering that millions of Venezuelans are refugees elsewhere in South America where they have no interest in further destabilisation.