I recalled someone ask this same question years ago.
Personally, I think it’s not a good idea.
2 issues that came to mind.
1) If pump died or power went out, you will likely flood the display tank.
2) if the drain line clogged, then you will flood the sump.
it’s doable, but will most likely beat the purpose of having a nice display tank. Unless you preferred to have a display tank with low water level line in order to accommodate the water from the sump if power went out or pump died.