But because of differences between GaN and Si, the selection of reasonably compatible controllers and gate drivers is smaller. For example, many ICs made for Si are underperformers for GaN, or they might need some "translation" circuitry because of different gate voltage requirements.

There are certainly many gains to be made with GaN-specific supporting ICs, but that hasn't really happened yet. My personal threshold for acknowledging a fundamentally different technology would be replacing all the Si in the gate drive loop with GaN. The idea is to not hold back the GaN switch from realizing its full potential with slower and less efficient Si.

The GaN switch itself is, of course, quite different from a Si power switch.

Ones designed with power electronics use in mind are made intentionally close to silicon FETs on specs.