Then, in the next couple commits, fix each conflict via a normal commit that mixes and matches "mine" and "theirs" as needed + deletes the markers.
Each resolution commit is independent of the giant merge commit, and can be separately diff'ed and code reviewed via the github PR or any other tool.
Also easier IMO to make the complicated resolution you want, or reset back to a previous resolution attempt without messing up the entire merge.
The drawback is that some commits won't compile, but compilable mid-branch commits are not something that I view as a goal.