I opened #27609 to keep track of multiple completion issues.  Some additions to what I said above.

1. I would like to move the actual fetch code to run.py, since it is normally executed in the user process.  See #27534, but also below.

2. Idle currently differentiates between completion invocation by <tab> or '.' and by <<force-completions>>, which defaults to Cntl-space.  I believe a main difference is that it will only call functions in the object expression, as in "f().", in the latter case.  I believe the distinction operates by calling for completions or not. (I need to check.) 

That distinction can be used here by only importing with <<force-completion>>, and then it should.  With that limitation, I think I am now in favor of adding this.  Importing a module is roughly equivalent to calling a function.  Either can do anything.  But the distinction has be known within the fetch code.  This could be done with a wrapper function.