Permit (restricted topology) submitpackage RPC outside of regtest. [...]
This RPC should be safe but still experimental - interface may change, not all features (e.g. package RBF) are implemented, etc. If a miner wants to expose this to people, they can effectively use "package relay" before the p2p changes are implemented. However, please note this is not package relay; transactions submitted this way will not relay to other nodes if the feerates are below their mempool min fee. Users should put this behind some kind of rate limit or permissions.

ninja all check-all