There are different solutions for this problem, depending on the system requirements. For example, if the system doesn't require internet to work, URLs doesn't makes sense they cannot be shared since the server/service behind them cannot be reached. However, we can observe other techniques and projects that use fault-tolerant protocols to share data over a noisy, lossy channel. I'm thinking of data over audio, where data is transmitted encoded in audio. Normally, the protocols used there have well-designed fault tolerance and tones to indicate the beginning and end of the stream. You can do the same and have chunking, sequence start bytes, and end bytes. This way, you can check data integrity too.

If the system requires internet to work, it can be resolved in multiple ways, from URLs to pure Nostr. I was already experimenting with the concept of using derivation paths to share Cashu tokens. For example, let's say we have a shared secret, like a Diffie-Hellman key exchange, which becomes our seed from which we can generate and derive new addresses. Knowing that, we can just exchange a derivation path with a fixed length. Then, with that derivation path and a relay hint, we can use NIP-60 to find the tokens. This can also have a different design approach where I expose an extended public key (xpub) from which you can derive addresses that only I control, and then share the derivation path of the key you used to lock the tokens.