Fully agreed with the usefulness of topgrade.
Topgrade is not just for archlinux but will happily upgrade Debian-/RedHat-Derivatives, Gentoo, Void, some BSDs and I think even Mac and Windows, though I'm not sure how those work.
The link you provided also goes to the unmaintained original version, while there is a community fork here: https://github.com/topgrade-rs/topgrade which sees more development (but is also looking for maintainers!)
I'm also using topgrade and it is wonderful to upgrade the system dependencies but even the content of unrelated package managers such as pipx, vim, zsh plugin-managers, cargo programs, R packages, npm/yarn packages, and importantly for this thread flatpaks and snaps with one command. It really is lovely.
Additionally, at least for my use-case btrfs benefits me since it is less picky about drive sizes being the same and duplicating everything correctly - letting you essentially just throw additional storage at it as you acquire it.