The cocoonjs can still be used, just go on exporters, click the right button and then select "Show exporters deprecated".
The cocoonjs IAP is working perfectly with the latest fixes in the plugin:
The scirra ended his official support, but not been happening a long time. Users can still keep the plugin updated.
As for the crosswalk, he will be a viable option for this sort of thing, but definitely at the moment, together with the construct, it does not support anything related to google play (leaderboards and IAP) services.
I do not think is valid encourage users to use something that is not yet complete, but certainly is worth getting informed about, because it is by far the most promising option.