Could be workable. I think the first needs to be only on classes, not interfaces, or you could still end up with Oreos overloads when you implement multiple interfaces. Not sure if generic type arguments cause problems. And I wonder about how extension methods appear in JS - haven’t checked.
The latter maybe works only if the overloads are all disjoint classes (given Alexey Andreev’s comment Mandatory method mangling when compiling to JS - #2 by Alexey.Andreev), not inheriting classes or interfaces - which is a bit of an odd restriction for Kotlin in general. But maybe this one could be implemented in a third-party annotation processor if it’s not general enough.