allow only one category in woocommerce cart plus hide price in a cat

woocommerce-category-limit.php

// only allow one category to be purchased at a time
add_filter( 'woocommerce_add_to_cart_validation', 'dietweek_only_one_product_category_allowed', 20, 3 );
function dietweek_only_one_product_category_allowed( $passed, $product_id, $quantity) {

    // Getting the product categories term slugs in an array for the current product
    $term_slugs   = wp_get_post_terms( $product_id, 'product_cat', array('fields' => 'slugs') );

    // Loop through cart items
    foreach (WC()->cart->get_cart() as $cart_item_key => $cart_item ){

        // Check if the product category of the current product don't match with a cart item
        if( ! has_term( $term_slugs, 'product_cat', $cart_item['product_id'] ) ){

            // Displaying a custom notice
            wc_add_notice( __('Only items from one product category are allowed in cart'), 'error' );

            // Avoid add to cart
            return false; // exit
        }
    }
    return $passed;
}
/**
 * Bonus. Hide prices of specific category
 */
// Specific product category archive pages
add_action( 'woocommerce_after_shop_loop_item_title', 'hide_loop_product_prices', 1 );
function hide_loop_product_prices(){
    global $product;

    if( is_product_category('PUT YOUR CATEGORY SLUG HERE') ):

    // Hide prices
    remove_action('woocommerce_after_shop_loop_item_title', 'woocommerce_template_loop_price', 10 );
    // Hide add-to-cart button
    remove_action('woocommerce_after_shop_loop_item','woocommerce_template_loop_add_to_cart', 30 );

    endif;
}

// Single product pages
add_action( 'woocommerce_single_product_summary', 'hide_single_product_prices', 1 );
function hide_single_product_prices(){
    global $product;

    if( has_term( 'PUT YOUR CATEGORY SLUG HERE', 'product_cat', $product->get_id() ) ):

    // Hide prices
    remove_action('woocommerce_single_product_summary', 'woocommerce_template_single_price', 10 );

    // Hide add-to-cart button, quantity buttons (and attributes dorpdowns for variable products)
    if( ! $product->is_type('variable') ){
        remove_action('woocommerce_single_product_summary','woocommerce_template_single_add_to_cart', 30 );
    } else {
        remove_action( 'woocommerce_single_variation', 'woocommerce_single_variation_add_to_cart_button', 20 );
    }

    endif;
}