I am Brazilian and my husband is Italian. We are going to the US and he is applying for an ESTA but I can’t apply because my country is not specified on the list. Is there such thing as accessory ESTA for spouse?
ESTA, or more correctly, the US Visa Waiver Program (which is what the approved ESTA allows you to use to enter the country) is based on your country of citizenship. The citizenship of your husband (or parents/children/etc) is not relevant, and thus you are not eligible to use ESTA/VWP and must obtain a standard US visa.
As a longer-term answer, if you were to obtain Italian citizenship (based on your husbands citizenship) and an Italian passport, then you WOULD be eligible to use the ESTA/VWP programs - not because of your husbands citizenship, but because you could then apply as an Italian citizen yourself.