of the various postulated scenarios, i'm fond of the double tap and hold maneuver to enable "copy" mode and then bring up the magnifying lens on the text.
select what you want y dragging the finger then release.
go to new program, double tap and hold again, then the clipboard pops up and you select the text snippet.
now, in this scenario, there's already a problem: how does the system know when you want to start copying or paste an item (bring up clipboard window"?
perhaps the double tap and hold needs to always bring up the clipboard and there's a button to begin selecting text to copy. but that removes the elegance of double tapping and using the existing loupe with an extra couple steps.
it's not an easy UI problem with no keyboard or on screen buttons.
perhaps a two finger hold over text? or two finger double tap nd hold? how complicated can we make this?