Not going to work, I suspect. The 'triac' in a light dimmer is
actually a 'quadrac', which has a builtin trigger device, and isn't
readily available in larger sizes. Phase control like
in a light dimmer makes for non-flickering illumination.

There may be some like that, but all the light dimmers I've opened have a
diac triggering a standard triac. A lot of times a lamp will fail and short
the triac, so I've replaced them from time to time with whatever I had on
hand.