Nothing about Web5 relies on RDF, from my understanding of their work, so why are you talking about it?
Discussion
I found the link to their reference implementation, and it looks like soon = now, at least for a fair amount of the features from that areweyet site: https://www.npmjs.com/package/@tbd54566975/web5
Also, looks like nothing relies on RDF, so what was all that about again?
So what's the canonical form of their JSON?
The VCs appear to be orthogonal/separate from any of the app data storage/interaction layer, and I see they primarily use the JWT variant of VCs anyway. The data storage/interaction part is listed as DAG-CBOR, so no RDF involved. But aside from all these protocols there's a simple JSON canonicalization RFC here people should use instead of rolling their own, imo: https://www.rfc-editor.org/rfc/rfc8785