ATMega 168 PB bootloader questions

I ran across this wonderful new chip the other day, and I am loving the potential of all the new I/O pins (Digikey says 27!)

I ran across a thread that had a few people loading the regular 168 bootloader onto the chip. But my question is - Would I be able to use the additional pins, or would that require a new bootloader?

The bootloader doesn't have any effect on the extra pins.
However, you'll need a new core "variant" to access the extra pins using the Arduino functions like digitalWrite()...

That 27 figure is a little deceptive.

One of those is reset

Two more of those are used up if you use an external crystal.

So 24, vs the Uno’s 20. The 4 extras come from them removing a gnd and vcc pin, and making the pins connected to ADC channels 6 and 7 on the '328p in TQFP32 package into first class citizens - these four pins form a new 4-bit port.

I have the Atmega 168PB and I need burn the bootloader using the arduino uno board.
The problem is in the library don't has the controler.
In this case how I can bootloader the micro?