Interesting release here https://www.x402.org/
It appears like it is none chain specific, so a Cashu version seems possible.
cc nostr:nprofile1qyt8wumn8ghj7etyv4hzumn0wd68ytnvv9hxgtcpzemhxue69uhks6tnwshxummnw3ezumrpdejz7qpq2rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sugh36r