Here's a little cool little thing I just did. For a few minutes there I didn't think it would be doable. The bluetooth wouldn't connect to the xkey 37. There was no headphone jack. The modern circular charger wouldn't work on an iPhone older than 12. OS, OS, OS, so different than android...
But everything is in place in the end
https://youtu.be/FLZCySHW0UY