Although testnet4 is not experiencing expected behavior (block storms and too many empty blocks), Lightning is now available for testing on this network using LND v0.19.0-beta.rc1 ~>
Be free to open a channel with me: 030f289f0f931cd33cc3435dc5f5fc2a6a65bb0297327d43e82562aded10df74a7@zscl5v323mngmeyu33wyrlkqyc3emaiv7pdezxjfrtu5qegedvmotpid.onion:9735
More info PR merged: add testnet4 support ~> 
GitHub
Release lnd 0.19.0-beta.rc1 · lightningnetwork/lnd
Database Migrations
There are mandatory database migrations in this version. Downgrading to previous versions will not be possible.
Verifying the R...
GitHub
chain: add testnet4 support by guggero · Pull Request #9620 · lightningnetwork/lnd
Adds testnet4 support to lnd.
Fixes #8966.
Depends on btcsuite/btcwallet#994 and lightninglabs/neutrino#311.