Investigate ways to create a sync method for LDK Listen interface and BDK Wallet/Database
Could potentially re-use the BDK RPC Blockchain as an LDK block source but you'd end up with LDK SPV client polling the block source and BDK's wallet.sync()
Other options might be to have bdk::Blockchain be the source of chain data that lightning-block-sync polls and you can also have bdk::Database (or Wallet) implement LDK's Listen interface to accept updates from lightning-block-sync