Reprogram old smartphone as mp4 player?

Hello everyone,

As already described in the question above, I would like to reprogram an unused smartphone for my small child.

The phone: Samsung A52 fully functional.

Unfortunately, my child has been placed in a foster family for personal reasons and since I always want and am supposed to print out pictures for them, I came up with the following idea:

I was wondering if it would be possible to reprogram the aforementioned cell phone into an MP4 player. Since these Raspberry Pis are quite expensive, and a cell phone can essentially do the same thing, and these video and digital photo frames are just as expensive, I would really like to do this with my cell phone.

I imagine it like this:

Turn it on, and without touching the display or buttons, the video you previously saved to the device via Bluetooth starts playing. My child can watch, listen, and simply enjoy it. If necessary, you can remove the device from the frame and add or delete new content. Just like with digital photo frames.

Does anyone here have any idea how or if something like this would be possible?

I would really like to avoid having to buy an extra device as I would like to do this myself and I also don't want to see these prices anymore.