Beyond push payments this feature allows for two-way communication with a client. So this can help drive AMP route sharding, CoinJoin negotiations, as well as sending money to friends with emojis or depositing into exchanges with account ids.
Using key send
Enable in config. accept-keysend=1 in Application options.
Send to receiver
lncli sendpayment --dest=03e691f81f08c56fa876cc4ef5c9e8b727bd682cf35605be25d48607a802526053 --final_cltv_delta=144 --amt=100 --keysend
It can enable Unilateral (permissionless) payments