Do you have an old PC lying around gathering dust? How about a small-capacity USB flash drive sitting, unloved in a drawer? You can reuse your old computer and a USB flash drive by installing a tiny Linux distribution.
Mini Linux distros are great as they require fewer system resources than other options yet still deliver a whole operating system experience, and we have nine of the smallest Linux distros for you to choose from.
I think one of the smallest yet fully up-to-date distros around is Alpine Linux.
It might not be a perfect desktop because of Musl incompatibilities but hey, it has a ton of apps in the repos, if your usecase it’s simple it might be enough.