To qualify, each implementation must satisfy two criteria:

1. Enable businesses to accept BTC payments via Lightning Network
2. Do that face-to-face, (i.e., mom and pops and Box Top stores should be able to generate a Lightning invoice/QR code a client can scan to pay)

I leave out of the scope other blockchains and stablecoins. In this day and age they are objectively inferior to LN as a payment rail.