Look at https://breez.technology that uses L-BTC as back-end

the less one puts in the work of studying mainchain Bitcoin and lightning (LND in particular), the further behind they shall fall;

i think that LN and BTC are actually a good model of how the collective mind behaves when grounded in reality (math and energy in this case); in other words, it is a model for studying the Self; Bruce Lee studied the self thru a physical combative artform, Pythagoras thru math and geometry, Usain Bolt thru athletic performance, mushroom scientists thru the study of the mycelial networks, etc.;

L-BTC was a fun project, and it's going obsolete;

It was never really alive in the first place.

Liquid peg-in/peg-out is a great privacy tool for de-correlating UTXOs. For paying LN invoices, it's slow (must wait 2 Liquid block confs before payment is released) and inflexible (min 1000 sat invoice balance - Aqua refused to pay for this comment and I had to use another LN wallet).

I don't think its dead, but perhaps use cases are limited. I for one use it for peerswaps (https://www.peerswap.dev/) and I recently realized that Bull Bitcoin supports it. :)

Was it ever alive?

Kidding, it does seem to have more TX since there have been some wallets like Aqua using it to swap with LN. Still a long way to go IMO

You can check out the Liquid block explorer its' pretty much a ghost town. If you have a lightning channel set up you're pretty much good when the high fee times come around

Some wallets are using Liquid to do lightning swaps into liquid on the fly via Boltz exchange like Marina wallet etc so that sometimes fills blocks You can rebalance channels with liquid too if on-chain fees is high

Liquid's main use was arbing between exchanges, but few support them

It was popular when ordinals made on-chain transaction fees spike and lightning custodial solutions were charging high fees to transact cuz expensive to open channels

As long as Blockstream is a company then liquid will exist