It is not a full replacement - but they are aiming for

Our current target is to build a drop-in replacement for all common use cases of sudo.

They are dropping support for some of the older/niche features/settings and now ignore some of the config you used to be able to do.

Some parts of the original sudo are explicitly not in scope. Sudo has a large and rich history and some of the features available in the original sudo implementation are largely unused or only available for legacy platforms. In order to determine which features make it we both consider whether the feature is relevant for modern systems, and whether it will receive at very least decent usage. Finally, of course, a feature should not compromise the safety of the whole program.

But generally for all common use cases it should just be a drop in replacement.