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This question still stands if anyone is able to shed some light:

Did you try?  Given the backend is deprecated, I doubt you'll get an official endorsement, but sometimes things like this just work.  Every project has a different set of criteria - so an informed decision would always require that you become familiar with the technologies through explicit/intentional experimentation before making a decision.

Having said that, it is hard for me to imagine a world where using the wasm32 target is a hard requirement for any project at the moment.  My advice would be to write as much platform-agnostic code in Kotlin common modules and use a well-supported backend (eg. JVM or JS) as your backend, and then you should be able to switch the code over to WASM with relatively minor effort once the new backend is available.