I am trying to merge a local branch into the master branch without having Git to do an automerge. I would like to “hand pick” what I would like to be merged into master.
I think you want to cherry-pick individual changes:
git checkout master
git log --reverse --oneline topic ^master
and then invoke git cherry-pick
for each commit you want to have in the master branch.
If the remaining changes in the topic branch should be preserved, you may also want to rebase this branch on top of the new master:
git rebase master topic