As of 2020 Bitcoin can almost-instantly be used as an interest bearing and yield producing asset, which is what "productive" means in this context.
There are both centralized custodial options as well as decentralized permissionless but custodial options, as well as decentralized permissionless noncustodial options. And yes, the yield is risk adjusted.
There are both centralized custodial options as well as decentralized permissionless but custodial options, as well as decentralized permissionless noncustodial options. And yes, the yield is risk adjusted.