FYI, if the goal is just to use something like an old Canon LiDE scanner (pretty common/cheap devices with no more driver support) on macOS: SANE runs natively and works great: https://formulae.brew.sh/formula/sane-backends (comes with `scanimage` CLI tool).
That is super helpful (I may well use it myself). But I guess a web app probably reaches some non-technical users that CLI tools don't.