Hello,
Loco is the only way to translate the theme, you can delete Loco after translation, please check the tutorial to see how to save the translation properly, and not lose the translation after the theme update or Loco deleting.
Here is a video tutorial that should help you translate your website texts with a Loco Translate plugin https://www.youtube.com/watch?v=D3NsDdMzsls&list=PLMw6W4rAaOgKKv0oexGHzpWBg1imvrval&index=3
Please check the video tutorial to see how to save the translation file correctly. You can remove the plugin and translations would remain. Also, translations would remain after each theme update.
In order to translate the WooCommerce strings, you need to create a separate translation in Loco > Plugins > WooCommerce in the same way as shown in the video.
Best Regards