Don’t ask Hacker News for legal advice. If you really want to know the answer, ask a lawyer.
"Get some small amount of bitcoin and pay a VPS hosting provider in Moldova for a year's service on a $15-per-month equivalent KVM VM and put what you know on there anonymously as static content, then publish the link here."
Not that a sufficiently dedicated nation state federal crime agency or intelligence apparatus probably couldn't trace back to you, but it raises the bar for something like random civil lawsuits from piano companies.