I actually like your idea better. The way I envisage it working would be that you could set ONE observation as your “feature” or “priority” observation, and while it is in the needs ID pool it would be brought to the front no matter how old it was. Once marked reviewed, it would drop out of the needs ID pool for that identifier, so would not continue to show and be “in the way”. In other words, all that would need to be done would be to have the Identify page put all featured observations ahead of all others, regardless of the sort order, ie sort on the featured flag first, then the other sort criteria. Perhaps in the filter box you could turn off the “featured first” setting, but it would need to be default to be effective.
The majority of specialist identifiers of course would be using custom queries anyway, so they are likely to not have their workflow affected, but for those just using the standard Identify page, it would mean they are always looking at “priority” observations before any others, and as soon as they attain RG status they would naturally drop out of the needs ID pool and so the “featured” status becomes irrelevant and it would be on the observer to then select a new featured observation. At no stage would they become unnecessarily “in the way” as far as the Identify page is concerned!
I could imagine that it wouldn’t have to be limited to ones own observations, either. You could set someone elses observation as your featured observation, just because you want to know the ID of that observation more than any other in iNat, including your own. if you found yourself in the situation where you had a (legitimate) need to find the ID on 3 observations with a degree of urgency, then you could ask other iNatters if they had their feature slot free,and could they feature one of your 3 to help you out. A slight possibility of encouraging sock puppet behaviour, but it would be comparable to the existing potential of sockpuppeting to confirm or weight ones own IDs at present.
By having it limited to one observation per iNatter, the potential for abuse or over-use would be somewhat mitigated.