Exhibit 10.3

JOINDER TO AND AMENDMENT OF THE

REGISTRATION RIGHTS AGREEMENT

This JOINDER TO AND AMENDMENT OF THE REGISTRATION RIGHTS AGREEMENT, dated as of April 22, 2025, by and among Texas Ventures Acquisition III Corp, a Cayman Islands exempted company (the “Company”), TV Partners III, LLC, a Delaware limited liability company (the “Sponsor”) and certain other parties thereto (the “Agreement”) is delivered and entered into in accordance with Section 5.2 and Section 5.5 of the Agreement. Capitalized terms used and not defined herein have the meanings given to them in the Agreement.

WHEREAS, the Sponsor is selling and transferring all of its securities in the Company to Yorkville Acquisition Sponsor II, LLC, a Florida limited liability company (“YA Sponsor”);

WHEREAS, YA Sponsor desires to be joined as a party to the Agreement;

WHEREAS, YA Sponsor will not be a party to the Insider Letter referenced in the Agreement, and as such, will not be subject to the transfer restrictions set forth in such Insider Letter; and

WHEREAS, the Agreement will be amended to remove the application of any lock-up obligations on YA Sponsor upon the acquisition of the securities of the Company which it is acquiring.

NOW, THEREFORE, YA Sponsor agrees to become a party to the Agreement, and shall accept and be subject to, and comply with the terms, conditions and provisions of the Agreement that apply to the Sponsor other than any transfer restrictions as defined in the Agreement under the terms “Founder Shares Lock-up Period” and “Private Placement Lock-up Period”, and YA Sponsor shall be entitled to the rights and benefits of the Sponsor under the Agreement.

[Signature page follows]

In witness whereof, the parties hereto have caused this Joinder to and Amendment of the Registration Rights Agreement to be duly executed and delivered by their proper and duly authorized officers as of September 18, 2025.

	YA SPONSOR:

	YORKVILLE ACQUISITION SPONSOR II, LLC

	By: YA II PN, Ltd.
	Its: Sole Member and Manager

	By: Yorkville Advisors Global, LP
	Its: Investment Manager

	By: Yorkville Advisors Global II, LLC
	Its: General Partner

	By:	/s/ Troy Rillo
	Name:	Troy Rillo
	Title:	Partner

	ACKNOWLEDGED AND ACCEPTED:

	COMPANY:

	TEXAS VENTURES ACQUISITION III CORP

	By:	/s/ E. Scott Crist
	Name:	E. Scott Crist
	Title:	Chief Executive Officer

	SPONSOR:

	TV PARTNERS III, LLC

	By:	/s/ E. Scott Crist
	Name:	E. Scott Crist
	Title:	Managing Member

Texas Ventures Acquisition III Corp 8-K