Do you mean post-actuation travel? With a Cherry MX switch (or clone) and most keycaps, you can reduce key travel below the actuation point with
O-rings.
I don't think there is any Cherry MX clone that has the actuation point lower down than regular Cherry MX, but many switches that actuate earlier (higher up) exist.
Kailh also has a few low-travel mechanical switches, such as the
Kailh Mini Choc PG1232 with total travel of 2.4 mm and both pre- and post-travel of 1.2 mm. You would need Kailh's own keycaps and other hardware.
There are several other low-travel switches from Cherry, TTC and Greetech but I think the Kailh Choc Mini has the shortest post-travel distance.
Some switches also have
hysteresis which means that the deactuation point is higher up than the actuation point. It means that a key has to be released higher up before it can be actuated again.
Hysteresis is found in many clicky mechanical switches such as Cherry MX Blue. It is rare in non-clicky switches but e.g. Topre switches have it. (Of course, keys don't have to be bottomed out to be released.)
For electric-contact switches, debouncing has to be done on
at least either key actuation
or key de-actuation. It is most often done on both. (Commercial keyboards often do both and have longer debounce times as long as of 30-40 ms just in case there is an imperfect switch, it would not cause QA to fail or returns).
For maximum performance in a chording system you should also make sure that your firmware does not do debouncing on merely one key at a time (The free popular firmwares TMK and QMK do that ... although I do not think it matters in practice).