What is a good brand name or, better yet, a good model for metal detecting? I want to put it on my Christmas list. I've decided 100 hobbies are not enough, I need one more.

Depends on how much $$ > $$$$ you want to spend :-)

Minelab
Whites
Tesoro
Garrett

Whites and Tesoro are both out of business if I remember correcty. Garrett, Minelab, or Nokta Macro. Anything in the Garrett Ace or At line is a good choice. Minelab Vanquish or Equinox models. In Nokta the Simplex is a good mldel with a lot of features but no a large price tag, the legend, and Impact are slightly higher priced options from Nokta. I currently have a Garret AT Pro and a Nokta Simplex plus. I am more comfortable with the AT Pro but only because I have more time on that machine.

Also put a pinpointer on list too. All 3 brands mentioned have pinpointer options.

One other thing, get one youtube and listen to the tones each machine makes, it would be rough if you got a machine only to discover you cant stand the tones it makes.

Warning its addicting and once you have one machine you will want another one or twelve.

I knew Whites and Tesoro were out of business, but their detectors are still available to find as used and are good :-)

Kellyco is a great place to see most if not all of the available options. I have purchased 2 machines for my kids from them with no issues.Kellyco Metal Detector Sales

Used machines didnt even cross my mind. It should have because I bought my Nokta used off of facebook market place. And my dream detector is a Minelab etrac even though it has been discontinued.

X2 on Kellyco. I bought my Minelab at their store right outside Orlando. Nice place to visit , big showroom with a bunch of ' test beds ' to try before you buy. Good people. Good prices.

What’s a pinpointer used for?

Generally locating a "target" more exactly.

When you have located a target , the pinpointer narrows down the search by a lot and saves a lot of digging.

I kinda thought that, but wasn’t sure.

Go with minelab or Garret

Minelab will give you more technology for the dollar

Watching

Moosetrot

Nugget shooting, coin hunting? 500$ or 5000$?
Hard to beat minelab but you pay for it up front

Minelab are excellent machines but there is a "learning curve" and an understanding of responses. . . they are NOT "turn-on and go machines.

Yeah out of the ones I listed a Garrett Ace machine is probably the closest to a "turn on and go machine". Fairly easy to use as a new user.

My advice to Md'ing newcomers' is to buy a good starter machine, . . that doesn't mean expensive! So many people spend $$$ and when they don't find "treasure" or learn how to use it properly, they stick it in a closet or basement and forget about it. . . . AND . . . that's where you can find some real GREAT deals on high $ machines if you search! . . . just don't get swindled on a piece of non-working junk! :-)

Do some research on the nokta simplex. I think you will be happy with it.

Ol dad

If you are going to hunt on grass, parks, beaches and such a multi freq. will shine. If you want to hunt plowed fields, broken ground the single freq. machines work better. I've owned most of the high end detectors at some point. If you want a do all the minelab equinox can be run single or multi freq. I'm not a fan of the straight shaft , kills my arm after a bit. The best all arounder for the money imho is the garret apex. It can run single or multi. Made in the usa and has a great warranty. Good luck