The challenge with adapters is that different batteries communicate different things to a tool, such as internal temperature, in different ways.

You cannot just connect + to + and - to -.

What could work is a battery with a new standardized interface, and modular adapters that can match different brands' tool interfaces.

Over the years, maybe some brands might develop tools that mate directly to the universal battery.

But now there are 18V/20V Max, 24V Max, 36V/40V Max, and 54V/60V Max cordless systems. There's no practical solution for this.