Without doing a residency in the US/Canada, they will not be board eligible in the US (rare exceptions that don't apply here exist). Although in the past, it was relatively common for US fellowships to accept folks knowing they would not be eligible for boarding in the US (at one time part of a residency, now the whole thing), this has become uncommon currently although I can't give you a number. Of course, your friend would generally also need to have completed the USMLEs and done reasonably well on them to land a fellowship. Note that GI is combined with hepatology for fellowship in the US and is among the more competitive pedi fellowships, although not on the level of adult GI or some other pedi fellowships. Since you asked, among the least competitive fellowships are renal and endo. Even these however might or might not still consider those who have not done any residency in the US/Canada.
My current advice? Your friend should decide if he wishes to permanently reside in the US. If so, then he should plan on doing a residency here if they are competitive for that. Lots and lots of folks have done two residencies for this reason. If it is to be trained to go back to his home country, this is not an ideal route to plan to come to the US just for fellowship at this time, even ignoring current political issues. Note that our fellowships require two years more of less of research in the 3 year total.
