Which the ancient Egyptians clearly had

Likewise, why would they bother with balloons, at all? We know they were highly advanced, it seems more likely they'd just skip to planes?

You need high current, not voltage. Electrolysis of water starts somewhere around 1.5V

I'm assuming you subscribe to the Baghdad battery idea? Even that would produce only a tiny amount of electricity if it did at all. It definitely couldn't be used for this or even the lighting idea some crazy people support. It may have produced a tiny jolt and have been used for religious purposes as they couldn't explain the small shock.