i think there is a proper name for the acinq java based lightning node... phoenix is just the mobile deployment of their LSP, i forget ... lemme dig up the github

https://github.com/acinq

yes, their full lightning node is called eclair

so you can run an eclair lightning node and use this feature connected to other eclair nodes 

 but yes, if only phoenix does bolt12 rn then only phoenix

but if other clients have bolt12 it should be interop