should't this package have pnpm as makedeps?

I guess yes — pnpm is only needed at build time (pnpm install + pnpm tauri build), not at runtime, so makedepends is the right place for it.

One caveat: because package.json pins packageManager: "pnpm@11.1.3" and pnpm 9+ defaults manage-package-manager-versions to true, the system pnpm will try to fetch that exact version at build time. Set npm_config_manage_package_manager_versions=false in the PKGBUILD to keep the build using the packaged pnpm and avoid an undeclared network fetch.

should't this package have pnpm as makedeps?

I've fixed, should be fine, thanks!

The app won't launch from the desktop but works fine when launched in terminal. The .desktop file has Exec=io.github.lullabyX.sone but the binary is just sone. Adding sed -i 's/^Exec=.*/Exec=sone/' "data/io.github.lullabyX.sone.desktop" in package() before the install line seems to fix it for me.