Company: GIGGU
Filing Date: 2025-09-29
Form Type: 425
Source: 0001193125-25-221783
Chunk: 182

Company: GigCapital7 Corp.
Filing Date: 2025-09-29
Form: 425
Chunk 182
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 in that State.

3. . This Joinder may be executed in two or more counterparts, each of which
shall be an original and all of which together shall constitute one instrument.

[REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]

IN WITNESS WHEREOF, the parties hereto have executed this Joinder to Transaction Support Agreement as of the date first above written.

| STOCKHOLDER NAME |
| By:              |
| Name:            |
| Title:           |

| Address: |
| Email:   |

Shares of Common Stock beneficially owned on the date hereof:

IN WITNESS WHEREOF, the parties have executed this Joinder to Transaction Support Agreement as of the date first written above.

| GIGCAPITAL7 CORP. |     |                         |
| By:               |     |                         |
| Name:             |     | Dr. Avi S. Katz         |
| Title:            |     | Chief Executive Officer |

TRANSACTION SUPPORT AGREEMENT SPOUSAL CONSENT I [____________], spouse of [____________], have read and approve the foregoing Transaction Support Agreement (the “ Agreement”). In consideration of the terms and conditions as set forth in the Agreement, I hereby appoint my spouse as my attorney-in-factwith respect to the exercise of any rights and obligations under the Agreement, and agree to be bound by the provisions of the Agreement insofar as I may have any rights or obligations in the Agreement under the community property laws or similar laws relating to marital or community property in effect in the state of our residence as of the date of the Agreement.

| Date: ___________________                   |
| Signature of Spouse: ___________________    |
| Printed Name of Spouse: ___________________ |

EXHIBIT C

FORM OF

AMENDED AND RESTATED

REGISTRATION RIGHTS AGREEMENT

This Amended and Restated Registration Rights Agreement (this “Agreement”) amends and restates in its entirety that certain
Registration Rights Agreement dated August 28, 2024 by and among GigCapital7 Corp., a Cayman Islands exempted company (the “Company”), GigAcquisitions7 Corp., a Cayman Islands exempted company (the
“Sponsor”), and the other parties thereto (the “Original RRA”), and is made and entered into as of _________, 202[_], by and among the Company, the Sponsor, the other parties to the Original RRA listed on
hereto, and each of the undersigned parties that are stockholders of