There are no read-only mode in WordPress admin for custom post types including WooCommerce products. The only thing I can offer is to block/hide publishing meta box which contains ‘Update’ button. This way user will can not save any changes even if he/she makes them.
You can use “Meta boxes access” add-on for this purpose. Scroll to the ‘Product’ section and block ‘Publish (submitdiv)’ meta box for the selected role.
