Blackrock teaching customers how to self custody in its Prospectus.
https://www.ishares.com/us/library/stream-document?stream=reg&product=IUS-IBIT-J&shareClass=NA&documentId=2212465&iframeUrlOverride=%2Fus%2Fliterature%2Fprospectus%2Fp-ishares-bitcoin-trust-12-31.pdf