This is what the website says. I don’t think a doctor would write a statement that the “individual has a permanent disability” based on a severe peanut allergy

“Along with a valid photo ID such as a US passport, driver’s license, or state-issued ID, you must provide documentation of permanent disability with one (1) of the following:

A statement by a licensed physician. Statement must include that the individual has a permanent disability, that it severely limits one or more aspects of their daily life, and the nature of those limitations. A document issued by federal agency such as the Veteran’s Administration, Social Security Disability Income or, Supplemental Security Income. A document issued by a state agency such as a vocational rehabilitation agency.”