Yes, it's possible. I really like the P8 we have just as it is, but I have converted a different folding bike to IGH. It's not that big of a deal.

You didn't state any goal beyond just having an IGH, so we're operating in the dark about your required/desired gear range & etc.

An inexpensive conversion would involve a three-speed IGH wheel kit and a single pulley chain tensioner (under $20). Hmmm - you might possibly need vertical dropout anti-rotation washers as well (depending on whether those or the horizontals come in that kit), but they're available and not expensive.

BTW, on the high side, a Rohloff+eccentric bottom bracket conversion could run $2000!