If I have multiple subfolders that I wish to target at different countries, I'm thinking the ideal set up would be to specify rel="alternative" hreflang with a language AND country code (e.g. en-AU) and ALSO to geotarget that subfolder to the particular country.

That way, the pages would be showing up both in the country-specific results (accessed via Search Tools) because of hreflang, AND the more generic country results from regular searches, because of geotargeting.

Is this correct?

p.s. What would happen if you geotargeted a subfolder which had e.g. pt-BR hreflang value (i.e. Portuguese-Brazil) to just Portugal?