With NWC make_hold_invoice method created by @fmar I thought about a self-custodial P2P auction platform:
- Sellers sign up with nostr pubkey and a receive-only NWC connection secret that supports make_hold_invoice. They can then post items for auction
- Buyers sign up with nostr pubkey and pay for an item using any lightning wallet.
- Each time someone pays higher than the previous, the previous hold invoice can be cancelled
- Once the time remaining to claim the hold invoice is near to an end, the latest hold invoice will be settled and the buyer who paid for that item will win it. The seller and winning buyer can coordinate the delivery of the auctioned item via nostr messages.
The short time an invoice can be held (several hours) means that the item has to be quite active (multiple people outbidding per day) to ensure the auction does not end before users get a chance (this could be solved with autobids though, a nice NWC feature for buyers who connect their NWC wallet)
There is some trust in the seller needed (possibly done through web of trust)
hold invoice PR: 
other ideas for hold invoices: 
GitHub
NIP-47 Add Hold Invoice Support by frnandu ยท Pull Request #1913 ยท nostr-protocol/nips
Rendered
This PR introduces support for hold invoices in the Nostr Wallet Connect (NIP-47) protocol.
Hold invoices enable more advanced payment wor...
Alby Blog
Build Conditional Payment Logic Into Your App
"Hold invoices" let you build conditional payment logic and trust minimized escrow services right into your app on top of bitcoin. Learn how.