Muun won’t work for that because it doesn’t support the Lightning address LNURL format.
The best options are currently:
Wallet of Satoshi
https://walletofsatoshi.com
Alby
https://getalby.com
LightningTipBot
https://ln.tips/
Both Alby and LightningTipBot can be configured with Zeus to give you an instant mobile wallet.
https://zeusln.app
You can also get an address from other places like Strike, Zebedee, Fountain.fm and Stacker.news.
