I'm the tail end of 'Boomer' and I never even heard of using two spaces. But then again I'm a two-finger typist and it seems to be a old-school typewriter trick.
"The Complete Manual on Typography (2003) states that "The typewriter tradition of separating sentences with two word spaces after a period has no place in typesetting" and the single space is "standard typographic practice"."
Since working on a computer, post-Mac at least, stuck to the basics of typesetting, I'm thinking 'two spaces' went the way of the Dodo when people started being able to use fonts and having to lay out text like old-school typesetters.