At some point, if someone could get hair samples from Obama’s barber or saliva samples off of a drinking object, it could be submitted to ALL of the genetic testing companies in the hopes of a match.
"What about in a foreign country?" did you say?
One would clearly have to be sure said DNA source was legally abandoned by Obama and thus fair game in the eyes of the law in the source location state and any federal laws, etc.
Hair can only be used for familial type atDNA tests if one has hair samples with the root attached. And that would require extraction of that atDNA via a forensic lab. And of course a chain of custody would be essential, even if anonymous. Such forensic analysis is much more costly than the everyday retail atDNA tests offered by 23andMe and AncestryDNA which require cheek cell swabbing or a good amount of saliva in a tube. And then the data could be uploaded to GEDMATCH.com say using just initials and see what showed up, just like the police now do at GEDMATCH to see what they can find from a DNA sample as to close cousins or family. But it would certainly be helpful and maybe definitive if samples could be obtained from Barack and any of his alleged half brothers to compare.
Now hair could be used for a mitochondria mtDNA test like offered by FamilyTreeDNA and that could be compared to another person willing to provide a sample who is proven to be in the direct maternal line of Stanley Ann Dunham. But an atDNA type of test would be much better and get access to a larger database for comparison. I have been active in the use of genetic genealogy since early 2021 to help others as part of my genealogy hobby.