Don't forget that even if the 'flight mode' is technically possible - and I want to say that I think an assault cannon with one is not Rules As Intended - that this flying shield drone is getting shot at as long as it's staying in your vicinity. A wheeled/tracked drone that basically carries mobile cover has already been developed, tested, and considered "too expensive for practical use" (read: present-day soldiers' lives are too cheap to deploy a mobile cover drone with them).
The idea has existed since late WWII when amphibious assault ships had the problem of troops on board getting machine gunned into red confetti when the armored ramp went down, so the first redrawing was to add a second armor plate at an angle on that boarding ramp so when the ramp dropped, the troops had at least an inch of steel between them and the machine gun...up until they had to actually leave the ramp. An idea of making it detachable so that soldiers could pick it up and advance cover down the beach was proposed, but I don't think that it was put into production even as a prototype.
