I can recommend using the iphone with a music app of your choice as an external source. iphone and tracker are a very potent pairing in my workflow. Also for sampling garageband, youtube, spotify etc.
@merlin for this use case, I’ve raised the following wishlist item :
For now you need to go though minijack if you want to sample, and if you want midi in order to sequence with the mini and sample the sequence in it, you need to connect both minijack (for audio) and usb (for midi).
So that would strongly simplify the connexion with the host device (be it a mobile/tablet/computer), as the sampling would work directly with a simple USB-C cable connected.