The FreeShop is a great way to try out games before buying them as most games don’t have demos.
Developer Page: https://freeshop.pw/
How to change or add Background Music:
The latest build of the FreeShop supports custom Background Music. I usually install by default the same music you would find in the eshop. You can learn more about this feature here: https://freeshop.pw/freeshop-bgm-soon/