Based on what I last heard from merchants that accept it (e.g. Bitrefill), it's about tied with Ethereum for second in payment volume, after Bitcoin.
Because lightning is actually relatively scalable it doesn't broadcast every action to everyone.
See Bolt 7:
> Note that the htlc_maximum_msat field is static in the current protocol over the life of the channel: it is not designed to be indicative of real-time channel capacity in each direction, which would be both a massive data leak and uselessly spam the network
https://github.com/lightningnetwork/lightning-rfc/blob/maste...
https://blog.dshr.org/2020/01/bitcoins-lightning-network.htm...