Incomplete list of HP-HIL devices. I will credit the all the pictures one day.
Connector
The HP-HIL bus uses specific 4-pin, 6-pin, or 8-pin SDL connectors.
HP-HIL Keyboards
46020A ITF KEYBOARD
46021A ITF KEYBOARD
46021AD (QWERTZ)
46021AF (AZERTY)
46021B
46021C (QWERTZ)
46030A KEYBOARD, VECTRA
98203C (Nimitz)

Mice
46060A HP MOUSE
46060B
A2838A
BKS ELECTRONIQUE B1309A TRACKBALL

Other Devices
46020 / 92241A HP-HIL CABLE
35723A TOUCH BEZEL / TOUCH ACCESSORY
A 12-inch user-installable touchscreen bezel which provides touch interaction with the host computer. The HP 35723A features a resolution of 43x57 points maximum. — source
This may often be referred to as “35123A”, due to an OCR error in the HP-HIL Reference Manual PDF.
HP45911A Graphics Tablet

Source: HP Journal, July 1987, pg. 4
An 1 1 x1 1-inch graphics tablet with 1200-lines-per-inch resolution. — source
45262A AUDIO INTERFACE UNIT
45914A HP-HIL ACCESSORY CARD (150A)
HP-HIL card for the 150A and 150B. This allows the use of an HP-HIL mouse with these systems. This card is not needed with an HP 150 II since it uses an HP-HIL interface for the keyboard to which the mouse may also be attached. Note that the 45915A and 45890A both come with HP-HIL interfaces as well. — source
45915A HP-HIL ACCESSORY CARD W/ 384K RAM
Memory expansion card for the 100 Series that also includes an HP-HIL port.
46080A EXTENSION MODULE
aka 2.4 METER EXT
46081A AUDIO EXTENSION
aka 2.4 METER EXT (W/ AUDIO)
Document “HP-UX Installing Peripherals” (97005-90002) refers to this as “Speaker Module”.
I had been parsing “HP-HIL / Audio Extension” all wrong. It isn’t an Audio Extension. It’s an HIL extension with audio thrown in. That is, it is a TTL repeater with an 8 Ohm speaker in the same box, I guess cause there was room. — source
46082A AUDIO REMOTE EXTENDER
aka 15 METER EXT & RGB COAX, though the “RGB COAX” part is probably a red herring reference to the DE15 port. See more info here.
as far as I understand you cannot “program” the 46082 extension. It is just an extension if your console is far from the computer. You would use two of these boxes, connect them with a long 15-wire cable and then connect one side to the computers HP-HIL and Audio port and the other remote side to a HP-HIL keyboard and a speaker. —source
46082B 30 METER EXT & RGB COAX
The “RGB COAX” part is probably a red herring reference to the DE15 port. See more info here.
Same as 46082A, but with longer cable included? Source.
46084A ID MODULE
(Source. For Series 300 Machines)
46083A ROTARY CONTROL KNOB
46085A CONTROL DIALS
46086A FUNCTION BOX
Document “HP-UX Installing Peripherals” (97005-90002) refers to this as “Button Box”
46087A A-SIZE DIGITIZER
ANSI A/ISO A4 Size.
46088A B-SIZE DIGITIZER
ANSI B/ISO A3 Size.
46089A CURSOR
aka CDE4H-10-HIT
Document “HP-UX Installing Peripherals” (97005-90002) says this is for the 46087A or 46088A Digitizers. It was available separately or with a digitizer as “Option 001”.
It is described as:
“..four-button, cross-hair cursor.. .. It uses no additional power and occupies no HP-HIL addresses.”