Installing per files from the ‘direct downloads’ section (sublimetext.com/download):
Files:
sublime-text_build-4152_amd64.deb
sublime-text_build-4152_amd64.deb.sig
sublimehq-pub.gpg
the commands:
gpg --import sublimehq-pub.gpg
gpg --verify sublime-text_build-4152_amd64.deb.sig sublime-text_build-4152_amd64.deb
resulting in:
gpg: BAD signature from "Sublime HQ Pty Ltd <support@sublimetext.com>" [unknown]