Ken Karsh created a beautiful ambient loop using just his guitar into the new FAC Alteza! He's looping that inside of Quantiloop, with iFX Rack for the solo guitar over it.
Two noteworthy AU apps are FAC Alteza and iFX Rack. I saw a demo of Alteza being used for ambient loops and decided to try a meditation improv. iFX is what the solo guitar is processed with. Alteza was used for the ambient loop, which is ALL guitar. No synths were used here. Of course, Quantiloop Pro continues to be my go-to looper app. I really tried to get the meditative vibe (no shredding allowed).