No. A single Pila 17650 would exactly fit but would provide only 3.7-4.2V. The only stock lengths that Pila was designed to replace are:
3 cells: Use 2 Pila 17500 cells ("150S") + a 9V (7.xV) bulb
4 cells: Use 2 Pila 17650 cells ("168S") + 1 9V (7.xV) bulb
You also can add various combination of Surefire A19 and A14 spacers/extenders/adapters to a 3- or 4-cell light to use three Pila 150 or 168 cells (11.1+ volts) with a 12V bulb. In fact, 5Mega (FiveMega?) is currently selling a 700+lumen upgrade to the Streamlight Stinger that uses three Pila 168 cells with an A19 extender (and a MUCH brighter bulb).
To use a single Pila cell, you need a 3.7V bulb. Wolf Eyes, Pila, Microfire, and a few other brands have designed their xenon lights to "switch hit" between Pila cells and regular 123A cells. For their 2-cell lights, you must replace the 6V lamp assembly with a 3.7V (or vice versa). For their 3-cell lights, the 9V lamp assembly will work just fine with either 3 123A cells or 2 Pila cells. For their 4-cell lights, a 12V lamp assembly will provide about two-third the light on two Pilas; a 9V lamp is recommended if you'll be using Pilas, but if you use the 9V lamp full-time and want to use 123A cells as a backup, you'd better have a 0V spacer to use as that fourth cell.
A few of the premium (over $100) single-cell LED lights are designed around the Pila.
I looked into Pila cells but I like to carry spares for all my lights and when I realized there were four combos of Pila diameter and length, I knew I wouldn't have the discipline buy lights of just one combination. So I'm standardizing on rechargeable 123A (RCR123A) cells:
1-cell LED lights designed to thrive on 3.7V
2-cell xenon lights fitted with a 3-cell lamp
3-cell xenon lights fitted with a 4-cell lamp
Now if only someone made a 15V lamp assembly for 4-cell lights...