This is an (around) ten seconds shot purely hand-held (without support), but the camera I used means almost cheating : a Minox 35EL.
the Minotar lens is relatively short focal (35mm)
the shutter release is very quiet
the viewing is permanent (rangefinder style)
the shutter is electronic : you only have to open it, stay still and wait until it automatically closes.
This image shows an interesting Xmas decoration in a french gothic church: suspended Xmas trees !
and these are two other handeld shots made with the same camera but maybe a little shorter (around 4 seconds).
The first image shows a statue in a sicilian church equipped with an electric neon glory. The second, my daughter aged 20.
I could also show other pictures made with a Yashica Electro 35, even longer exposures but not strictly hand-held (with the help of some opportunistic support). Anyway, rangefinders with electronic shutters are very convenient for such long exposure times.