If there are no qualified studies identified within the said scope/topic, it indicates that a new original study is needed, and you are the one person who find out about this. Hence, you better conduct an original study on this topic with the other authors. You can also do a scoping review or a narrative review about this issue and emphasize the fact that the existing studies in this domain do not pass the risk of bias checklist items (all of them are underqualified), that is why there is a literature gap and someone need to conduct a new original one.

I think it should be an interesting short communication or letter to the Editor of relevant journals

Ideally, yes it can be considered for publication, especially if the knowledge gap is clinically relevant and if the question is directed towards experimental study designs including clinical trials. However, with association based research typically observational studies, they don't rank very high in priority for publication as they may only give you a valid hypothesis which needs proof through trials. Most of the journals these days a re looking at high quality RCT based SRMAs than empty reviews, which means a high level of publication bias. In years gone by, I think even Cochrane published some empty reviews, but today its all a matter of citations and h- index, so unless the question is very targeted and clinically relevant, publishing may be a challenge. All the best for your work and good luck!