Can I use the filter function to prevent files of less than (or greater than) a specified size from being displayed in the list?
No, filtering is done only by name. There are no other predicates.
However you can use custom lists and an external program like find:
find
:!find -maxdepth 1 -size -100c %u
I see! So you can handle a list of files generated by an external command? This is great. Thank you!
So you can handle a list of files generated by an external command?
Yes. You can also use %U to avoid resorting output in case there was a particular sorting. There are two more related macros.
%U