The Lightning protocol operates in millizatoshis. Including the LNURL (and NIP-57). But for some reasons unknown to me, the developers of LNURL solutions often ignore this and round it up to a thousand (1 sat). I patched the snort a little with my hands so that I could specify fractional parts. More than 90% of NIP-57 providers do not work, but the jp55 lightning address works with msats. And I sent to him 1/1000 of satoshi 😃