Orders menu is protected by ‘edit_shop_orders’ capability. It’s possible to prohibit new order creation if you activate ‘create’ capability at User Role Editor Settings.

But ‘edit_shop_orders’ capability is enough to ‘process’ and ‘complete’ the order. The only way to allow a read-only access to the WooCommerce orders is to use this filter from WooCommerce code:

$actions = apply_filters( 'woocommerce_admin_order_actions', $actions, $the_order );

Your function for this filter should return empty $actions array for ‘editor’ role in order to make for them read-only access.

Let me know if you need further help.