FWIW, Can a whistleblower bypass IG/DNI and go directly to Congress? Yes, but....
https://www.justsecurity.org/66211/qa-on-whistleblower-complaint-being-withheld-from-congressional-intelligence-committees/
That being said, there are constitutional arguments to be made for a whistleblowers right to petition Congress directly outside of the ICWPA process; in fact, the ICWPA originally included a requirement which did not make it into the final law that the president must inform Intelligence Community whistleblowers of that fact, and 5 U.S.C. § 7211 specifically states that [t]he right of employees, individually or collectively, to petition Congress or a member of Congress, or to furnish information to either House of Congress, or to a committee or member thereof, may not be interfered with or denied.
The major pitfalls most often come when national security whistleblowers try to tell congressional staffers about their complaints. An agency may decide that even a congressional staffer with a security clearance lacks the need-to-know a classified whistleblower disclosure, and, according to a Justice Department Office of Legal Counsel (OLC) opinion, the agency can take adverse actions against such a whistleblower, such as revoking their security clearance. In fact, just such a case led to the passage of the ICWPA.
However, unlike a staffer, a sitting member of Congress does not require a security clearance and should be considered to have the need-to-know anything they want to know. Executive branch lawyers dispute the latter characterization (while acknowledging the former) and argue that members of Congress are not inherently authorized to receive all classified information, but agencies provide access as is necessary for Congress to perform its legislative functions. But this authority is a logical and inescapable outgrowth of the very separation of powers principles the executive branch so often cites. Simply put, need-to-know is a creation of executive orders, and executive orders cannot be applied to anyone outside the executive branch, especially not members of a co-equal branch. Legally speaking, this would also apply to congressional staffers, but Congress made a decision decades ago to compromise and concede the field to the executive branch on that count, which it did so by passing rules: House Rule X(11)(e)(2) and Senate Select Committee on Intelligence Rule 9.6.