Make product purchasable based on the vendor opening and closing time in dokan plugin.

dokan-add-to-cart.php

<?php
/**
 * Hide or display add to cart button based on opening hours.
 */
function prefix_woocommerce_is_purchasable( $is_purchasable, $product ) {

	// Get the store id.
	$store_id = get_post_field( 'post_author', $product->get_id() );

	// Get the store info.
	$store_info = dokan_get_store_info( $store_id );

    // Get the store time enabled or not.
    $is_dokan_store_time_enabled = $store_info['dokan_store_time_enabled'];

    // If the store time is enabled, check whether the store is open or not.
    // Else the store is open.
	if ( 'yes' === $is_dokan_store_time_enabled ) {
		$is_purchasable = dokan_is_store_open( $store_id );
	} else  {
		$is_purchasable = true;
	}

    return $is_purchasable;

}
add_filter( 'woocommerce_is_purchasable', 'prefix_woocommerce_is_purchasable', 10, 2 );