Isn't this going to busy-wait, esp. with the loop.call_soon() version?

Even with loop.call_later(0.1, tk_update) you're wasting battery power
even if no network activity and no UI activity is happening. I'm not
eager to document this as the right way to do things, even if it
unblocks some apps in the short term.

A proper solution IMO should somehow merge the selectors so that a
single select() or whatever wakes up when either network I/O happens
or a UI event comes in (which could be something that Tk transparently
handles but it still needs to be given the chance, through
root.update()).