Yes, they can confirm that you have a Signal account. They actually publish their subpoena responses so you can see exactly what information they have: https:/

Yes, they can confirm that you have a Signal account. They actually publish their subpoena responses so you can see exactly what information they have: https://signal.org/bigbrother/central-california-grand-jury/ https://signal.org/bigbrother/central-california-grand-jury/.