Replying to @wtrmt@mastodon.social
@wtrmt@mastodon.social @root42@chaos.social Sequoia added a setting in the Mac App Store to install apps larger than 1 GB to a an external disk: https://support.apple.com/guide/app-store/download-install-large-apps-a-separate-disk-fir06754f864/mac
Haven't tested it but from what I understand, it creates all the necessary folders (Applications, Library and so on) on the disk automatically.