What comes to mind, as I face changing out a DS headlight on my 1986 244GL, is my cordless electric screwdriver. (This is my third, wore out the first two.)

Is is straight, not angled, and has a small headlight.
With an adapter, hex to 1/4-inch square drive, and a set of small SAE and metric sockets and some extensions, it is very versatile. Not a lot of power, but great in odd spots, like the headlight job, voltage regulator/brush set removal, adjusting screws on alternator and a/c compressor, upward-going screws on the steering wheel housing.

Another is a small mirror, used with a small halogen flashlight. Easy to see the other side of things, like the bottom side of the tail light circuit board connection points, or the machine screws that go upward from under the steering wheel housing.

A 1/2-inch drive bending bar torque wrench. It cost less than the clicker type, and has worked well for the 30 years I have owned it; kept in its original box. Important for spark plug and wheel instllation jobs.

Not a tool, but good to have. A box of 100 vinyl gloves. Costs around $8.00 at the hardware store, paint department. Use a lot but no good for gripping an oil oil filter. lol

Good Luck,

Bob

:>)

PS Then there's the BGVPD full of Volvo stuff.