It can handle them, though we haven't built that much tooling around them. However, unlike GitHub, updates to PRs (Patches in Radicle) are non-destructive, just like Gerrit[0], and code reviews are tied to specific revisions of patches. This is in my opinion one of the biggest flaws in GitHub's model.
That's indeed the biggest flaw in the Github PR model. I've been hoping for a gerrit-like code review experience in a Github alternative for years. I'll be sure to try Radicle.
[0]: https://www.gerritcodereview.com/