So I have this app that plays all zx spectrum loading sounds, I'm looking for a device I can connect to my zx spectrum+2A that will load the game or is this possible with just the sound
It depends on if the device can produce enough volume.
As you have a +2A (which does not have any tape in/Ear input), you either need a “cassette tape adapter” and suitable lead. Or be prepared to modify it electronically inside.
If your device cannot produce enough volume, you would need an audio amplifier.