https://www.justice.gov/jm/jm-9-11000-grand-jury#9-11.140
Incorrect. For a better understanding of Federal Grand Jury subpoenas, see the information in the above link.
Subpoenas may be used to secure, among other things, bank records. This is particularly relevant to much of the FISA abuse regarding payments for the Steele dossier and other, related matters potentially including the SR 187 and 2 MS13 187's.
It can also be used to compel the testimony of uncooperative witnesses who must either put up (testify on record and step into traps) or STFU and plead the 5th. Pleading the 5th never looks good to a jury, does it?
Before you're ever charged with a crime, why not speak up and keep yourself out of trouble in the first place?
Oh hell yes, Grand Jury subpoenas mean quite a bit