Contract analysis

I. Engagement and Purpose We have acted as counsel to Pinnacle Acquisition Corp. I, a Delaware corporation (the "Company"), in connection with the initial public offering (the "Offering") of 20,000,000 units (the "Units"). Each Unit consists of one share of the Company's Class A common stock, par value $0.0001 per share (the "Class A Common Stock"), and one-half of one redeemable warrant (each whole warrant, a "Warra

II. Documents Examined and Relied Upon In rendering the opinions set forth herein, we have examined and relied upon originals or copies, certified or otherwise identified to our satisfaction, of the following documents:

1. The Registration Statement on Form S-1 (Registration No. 333-254891), as originally filed with the Commission, and all amendments thereto, including without limitation Amendments No. 1, No. 2, and No. 3 thereto;

2. The Prospectus, consisting of the prospectus dated May 24, 2021, as supplemented by the prospectus supplement dated June 22, 2021;

3. The Underwriting Agreement dated June 22, 2021, among the Company, the Sponsor, and Ridgeline Whitfield Securities LLC, as representative of the several underwriters;

4. The Warrant Agreement dated June 25, 2021, between the Company and Continental Dunmore Financial, as warrant agent (the "Warrant Agreement");

5. The Investment Management Trust Agreement dated June 25, 2021, between the Company and Continental Dunmore Financial, as trustee (the "Trust Agreement");

6. The Amended and Restated Certificate of Incorporation of the Company, as filed with the Secretary of State of the State of Delaware on June 25, 2021 (the "Charter"); and

7. Such other documents, records, certificates, memoranda, and instruments as we have deemed necessary or relevant to the opinions expressed herein, including certificates of officers and representatives of the Company and such other parties as we deemed appropriate. In our examination of the foregoing documents, we have assumed the legal capacity of all natural persons executing such documents, the genuineness of al

III. Assumptions In rendering the opinions expressed herein, we have assumed, with your permission and without independent investigation or verification, the following: (a) All documents submitted to us as originals are authentic, all documents submitted to us as copies conform to the originals thereof, and all signatures on all documents examined by us are genuine. (b) The transactions described in the Prospectus an

IV. Opinions Based upon and subject to the foregoing, and subject to the limitations, qualifications, and assumptions set forth herein, we are of the opinion that, under currently applicable U.S. federal income tax law: Opinion 1: Classification of Units — Treatment as Purchase of Two Separate Assets For U.S. federal income tax purposes, the purchase of a Unit should be treated as the purchase of two separate assets:

V. Scope Limitations and Qualifications The opinions expressed herein are based upon the Internal Revenue Code of 1986, as amended, the Treasury Regulations promulgated thereunder (including proposed and temporary Treasury Regulations), published administrative rulings, procedures, and pronouncements of the Internal Revenue Service (the "IRS"), and judicial decisions, all as in effect as of the date hereof. All of th

VI. Consent to Filing and Reference We hereby consent to the filing of this opinion as Exhibit 8.1 to the Registration Statement on Form S-1 (Registration No. 333-254891) filed by the Company with the Commission. We further consent to the reference to Calderwood & Harkness LLP in the Prospectus under the captions "Material U.S. Federal Income Tax Considerations" and "Legal Matters." In giving such consents, we do not

VII. Reliance Limitation This opinion is furnished solely to the Company for use in connection with the Offering and the Prospectus. This opinion may not be relied upon by any other person or entity, or used, circulated, quoted, referred to, or otherwise utilized for any other purpose, without the prior written consent of Calderwood & Harkness LLP. Notwithstanding the foregoing, holders of Units and their component s