Can you help identify this symbol?

I would go with a variable resistor but I do get some confusion by having a second similar component shown without the wiper connected. 0P means zero potentiometer or a resistor. Guessing mind you. 

Best guess is depletion mode nmos logic, but I'm not 100% certain. Take care 

Good luck, is it a restive keyboard?

This looks a schematic of circuitry internal to a chip and it looks like these could be substrate resistances. Note the connection is to VGG.

I seem to recall seeing this symbol eons ago, but it was before I was fully sentient, so all I can recall is the visual.

It might just be a FET of different construction/dimensions, perhaps used in place of a resistor (normal resistors take up a lot of real-estate on a chip), so perhaps they invented that symbol. Although they violate that concept by using the device as a FET when they connected the phiP and phiIP (on mobile, don't know how to draw the Phi symbol) as inputs to a couple of the gates. Anyway, perhaps they are lower-performance FETs basically. 

All my comment above is pure speculation however..

φ is one of the special characters under the insert menu. Does the mobile view not have this menu?

No idea. It was quicker to respond as above than to start clicking on tiny menus/icons.

I don't know when I'll ever absolutely need to type such characters while on mobile except once in a blue moon, so to me that didn't seem interesting to investigate.

Google'd a bit, and found this photo/diagram from Ken Shirriff's blogs showing an NMOS gate:

As can be seen in the photo, the gate is composed of two devices, the right side looking similar but slightly different, because that's a different FET (DMOS FET).

In the photo, the right side FET has it's gate connected to 'out' rather than +5V, but other than that, no real difference to what the Apple schematic shows. So I think the symbol they're using happens to kind-of look like a resistor because that's what they are using the device as. 

Having both a weak pull-up and a stronger one that gets enabled when it's needed (by a clock phase) was probably a way to get the chip power consumption down a bit.

I've seen the symbol elsewhere in material about chip design, so I don't think it's unique to Apple.

Here's another example of the symbol's use. This is the internal schematic of a Signetics 2501 SRAM from a 1975 datasheet. They've drawn it a bit more like the usual MFET symbol.

Intel preferred this, where they've simply shown where the implanted channel for the depletion device sits. This is from an application note explaining how the SRAM cells worked.