Yep! Whatever your wallet supports, put it in there!

bluematt

So I'd create a single BIP21 code with a stealth address, an LNURL a cashu endpoint and a Bolt12 offer for maximum interoperability?

bitcoin

Human Readable Bitcoin Payment Instructions

Yes, not only does this allow for multiple protocols, its reliance on BIP 21 URIs means it can reuse wallets’ existing multiple protocol logic!

> I don't understand why a wallet should fail the Lightning address if it finds multiple TXT records. Couldn't multiple TXT records be used to achieve the above, e.g. one record for a stealth onchain address, another for LNURLp, Bolt12, AMP or keysend?

BIP 21 today is usually implemented by providing a single URI with multiple payment protocols embedded in different query parameters. This takes advantage of that standard and uses a single record to express as many protocols as a recipient wants. It could be relaxed to allow multiple TXT records, but given there’s no need for it and it may cause ambiguity or indicate misconfiguration, it seems best to disallow.