Please elaborate more how is the "1BTC liquidity" related to LUD-14's balanceCheck.

Nobody owns no one.

It's just a belief system in your head. Each person thinks too much of themselves. Read some Daniel Kahneman.

It would be great if the guide mentions some expected data sizes. Remember zerofeerouting on Twitter having issues with huge DB compaction performed regularly (and taking their node off the network for a few hours?).

Another unrelated thing is they started believing the private channels are more stable in the long-term (which is/was just an LND-related issue).

I wish I had a smartphone :-P

If there is a browser on iOS that allows you to set a SOCKS5 proxy, you can run Tor on another device and connect through it.

What about doing some LN signmessage to get the information in the first place, instead of just calling a particular URL which anyone can do? If the attacker gets to the URL and gets a new randomly-generated balanceCheck URL for next time, the original owner needs to do extra steps to reset things and re-gain access. Of course no sats are stolen, but human time is.

Wonderful! Just please use some rate-limiting.

One can get many new invoices without paying them by just opening https://satoshis.lol/.well-known/lnurlp/joel?amount=5000

This would be a possible Denial of Service vector. For example it may cause your LN node back-end to use too much memory for all those unpaid invoices until it stops responding to new invoice requests.