Sincerely do appreciate the more cordial tone. But am afraid it is based on a fallacy that this is not a gap of LO Calc in comparison to its competitors.
FTR, Excel’s cell validation does provide full-text search autocomplete.

The previous screenshot already posted was Zoho’s spreadsheet tool. Google sheets does the same.
I’d definitely rather use open-source than proprietary MSFT or Big-Data cloud solutions, but push-comes-to-shove if there are simple functionality gaps and the attitude encountered above (*from other users) is the norm trying to address them; then back to big-data I go.