Short answer is No.
This has been discussed and raised before, see
http://4js.com/fjs_forum/index.php?topic=242 and also
https://4js.com/support/issue/?id=FGL-2389.
The restriction applies to all attributes (except Value) of a widget when used in a Table, Tree, or Scrollgrid, it is not just the ITEMS attribute but others such as STYLE, COMMENT, etc that you may want to manipulate on an individual row basis as well. When we review the Table as per our roadmap
https://4js.com/2019-genero-enterprise-three-year-roadmap-2/ then this is certainly an area I would be bringing up for discussion.
For now, the zoom window is the preferred solution. You can use presentation styles to make the zoom window look a little like a combobox, you can use NOTEDITABLE attribute on BUTTONEDIT to force user to select value from BUTTONEDIT, I have an example somewhere from a few years ago I should add to GitHub.
Reuben