After reading through the documentation for upgrading a Haiku installation:
Updating and downgrading your system | Haiku Project (haiku-os.org)
I noticed a paragraph under the section “Freeing some disk space”, which states:
When updating, old packages are kept in directories named “state_…” in /system/packages/administrative/ to allow booting with previous states in case update fails. After a while you might want to free up some disk space. You can safely remove the oldest state folders there, as well as the “transaction-…” ones. Do not touch the other directories though.
Keeping the above in mind, someone could possibly make a simple “Disk Cleaner” app for Haiku, that would search the abovementioned directories and ask the user whether they would like to free up this disk space.