Cypress: How to verify generated checkBox is checked and has attribute aria-checked="true"

I want to verify that a checkbox is checked. But it isn't a usually checkbox from type="checkbox", so it HASN'T the property "checked". Instead of this you can find in the HTML-Doom aria-checked="true". How can I read out this value?

HTML-Snipet:

<mat-checkbox class="mat-checkbox mat-primary mat-checkbox-checked" aria-label="checkBoxCapacityBaseEditDayofWeek: 1" id="DAY1">
  <label class="mat-checkbox-layout" for="DAY1-input">
  <span class="mat-checkbox-inner-container">
   <input type="checkbox" class="mat-checkbox-input cdk-visually-hidden" id="DAY1-input" tabindex="0" value="1" aria-checked="true">

What I've tried for so long:

Cypress-Code (nothing works):

// cy.get('#DAY2')
    // .should('have.value', 'aria-checked="true"')
    
    cy.get('#DAY1')
    .should('have.attr', 'aria-checked', 'false')

    cy.get('#DAY2')
    .should('have.attr', 'aria-checked', 'true')

    // .invoke('val', 'aria-checked')
    // .should('eq', true)
    // .should('have.prop', 'aria-checked', true)
    // .should('have.attr', 'aria-checked', 'true')

How can I get to the value true?

EDIT: I found the solution: Cypress-Code:

cy.get('#DAY1-input').should('have.attr', 'aria-checked', 'true')