Possibly a lightweight Kailh Choc linear switch? They’re very soft and quiet, but they have no tactility. The tactile ones leave a bit to be desired. It’s hard to match rubber domes there.
Indeed. Even if it's antithetical to the mechanical keyboard idea, I wish MX style keycaps (wide availability, for ex this is how I could get a Cyrillic keyboard) could be made compatible with rubber domes (with no mechanical switch)
https://mkultra.click/choc-switches