Hello! I have noticed that the Ckb Wallet Sdk is an ongoing project, so it could be that the mainteners didn't publish yet the packages in the npm/yarn registries. I believe - but I could be wrong because I don't have enough info - that:

[1] they started the documentation and then they didn't publish the packages and/or

[2] their packages are private, so you need login to access.

Anyway, I left this comment on their GitHub repo's open issue: https://github.com/Peersyst/ckb-peersyst-sdk/issues/1#issuecomment-1219116975