There's no specific client for displaying kind40 alone. Amethyst & Coracle.social support group chats.
https://unyu-house.vercel.app/ shows some chats.
Discussion
nostr:npub1q8w7u2ymrghfpp6v5dpg57jpgaj2djk340a2npwzq8n64ksk6wxq8aw95u Hey when I try to zap you using the "Zap Me" button at https://unyu-house.vercel.app/ I get the following error: `Error: failed to retrieve zap endpoint :(`