I go through a lot of emails and what I love recently is being able to sort by sender - then all the emails from the same person are together and it's easier to skim through ("yup, all these are uneeded except this unusual one")

Annoyingly thunderbird allow but not gmail, so I wanted to use thunderbird. But it doesn't easily allow archive-ing, like GMail does.

Contrived but still easy solution: tag all your inbox you want to go through with two labels SetA and SetB. Open SetA in thunderbird, using `a` to remove emails from SetA as if you archived. Then in GMail, use the search `label:setB - label:SetA` and it gives all the emails you wanted to archive. Archive those and done