1. Github's UI doesn't really support reviewing individual commits in a big PR.

2. It also can't merge subsets of commits from a single PR. E.g. if you have two commits, A and B, where B depends on A... sure you can make a PR containing A and B, but if A gets approved and B doesn't, then you can't merge A.

3. The thing you want to do with a set of commits and reviewing each commit IS stacked PRs.

This is nothing to do with AI.