pKa values will give some indications though, at pH above +/- neutral, metal hydroxide formation starts messing with theory and 1+1=2 logic.
Most acids only work well in their dissociated (basic) form. Unlike citric and edetic acid, gluconic acid does not just interact with their carboxylates but also with its pH independent hydroxy groups (‘good’ chelates also contain amine groups which react in an opposite way to pH). Interactions with hydroxyls are quite weak but may still work to a degree; whether or not this suffices remains questionable. I doubt that these metal complexes will be inaccessible to microbes and there’s indications (publications) which have me believe that those low pH complexes are even worse regarding fatty acid oxidation than free metals (unless the increased solubility draws them out of the oil phase).
Phytic acid on the other hand has such low pKa values that it’s essentially always deprotonated enough to complex metals even at very low pH whilst it simply precipitates at higher pH (which, from a ‘get the metals out of the way’ perspective, is the best outcome though might not be from a cosmetic point of view if there’s too much deposits).
Citric acid will not properly work below pH 5 whilst gluconic acid is maybe better than nothing. EDTA as an example has 100 to 1’000 times tighter binding to metal ions at pH 7 compared with pH 5. Unfortunately, there seems to be no useful investigations for poor chelates such as gluconic acid. It’s a PITA to find anything useful regarding gluconic acid metal complexes.