Circuit review of 'pulse in, hold on'
The usual suggestion is to use some NE555 timer as a monostable for this, indeed. But honestly, your solution is perfectly fine. And if you use something like a 74LVC2G14 for the two inverters, it will even take less board space than a 555 configured as a monostable.

Note that the 555 takes an active-low trigger input, unlike your current circuit. So you may require an additional inverter if you don't have the possibility to change the polarity of the input.

But there are still a few differences in corner cases:


You must be aware that, in your circuit, your RC timing starts when you release the trigger. That is, when the input goes back to low. So the output pulse will be: input trigger pulse length + timing constant. Whereas with the 555, the capacitor starts charging as soon as the trigger becomes active, and the trigger pulse length does not have any impact on the output pulse.
For the same reason, with a 555, if you get spurious triggers during the time the output is still high, these triggers are ignored. Whereas in your case, if you retrigger while the output is still high, the capacitor discharges again you will end up with an output pulse longer than the usual. Whether it is good, bad, or irrelevant depends on your application.
Also, when you power up your current circuit, you'll have an unwanted output pulse because the capacitor is initially discharged. If this is a problem, tying the capacitor to VCC instead of GND should fix this.