Company: GIGGU
Filing Date: 2025-09-29
Form Type: 425
Source: 0001193125-25-221783
Chunk: 225

Company: GigCapital7 Corp.
Filing Date: 2025-09-29
Form: 425
Chunk 225
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 address is [_].

This certificate is made in accordance with the requirements of Treasury Regulations Sections
1.897-2(h) and 1.1445-2(c)(3). Target understands that this certificate may be disclosed to the Internal Revenue Service by Acquiror and that any false statement
contained herein could be punished by fine, imprisonment, or both. This certificate constitutes authorization for Acquiror, as agent for Target, to deliver this certificate, along with the appropriate notification, to the Internal Revenue Service on
behalf of Target.

Under penalties of perjury, I declare that I have examined this certificate and, to the best of my knowledge and belief, it is true, correct and complete, and I further declare that I have authority to sign this document on behalf of Target.

|                  |     | HADRON ENERGY, INC. |     |        |
| Dated: [_], 2026 |     | By:                 |     |        |
|                  |     |                     |     | Name:  |
|                  |     |                     |     | Title: |

2

Exhibit 10.1

Execution Version

SPONSOR SUPPORT AGREEMENT

This SPONSOR SUPPORT AGREEMENT (this “”), dated as of September 27, 2025, is entered into by and among
GigAcquisitions7 Corp., a Cayman Islands exempted company (the “”), GigCapital7 Corp., a Cayman Islands exempted company (“”), and Hadron Energy, Inc., a Delaware corporation (the
“”).

RECITALS

WHEREAS, concurrently herewith, the Company, MMR Merger Sub, Inc., a Delaware corporation (“”), and
GigCapital7 are entering into a Business Combination Agreement (as amended, supplemented, restated or otherwise modified from time to time, the “”), pursuant to which (and subject to the terms and conditions set forth therein)
Merger Sub will merge with and into the Company (the “”), with the Company surviving the Merger as a wholly owned subsidiary of GigCapital7;

WHEREAS, capitalized terms used but not otherwise defined in this Agreement shall have the meanings ascribed to them in the BCA;

WHEREAS, the Sponsor is currently the holder of record and the “beneficial owner” (within the meaning Rule 13d-3 under the Exchange Act) of 10,107,246 shares of GigCapital7 Common Stock (the “”) and 3,719,000 Cayman Purchaser Private