The equipment you listed is exactly what I would have suggested as a genral starter pack.
Sewing machine is a no-brainer. The "pizza cutter" is called a "rotary cutter" and is favored by most people. The mat is a requirement to use the rotary cutter.
Anything that could be useful to her after that depends on what she makes, but a few ideas include:
Pincushion wristband
As the name implies, it's a pincushion you can strap around your wrist like a watch. That way you have both hands free to manipulate the fabric but always have your pins nearby.
Pattern weights
If your wife uses tailoring patterns for the objects she sews, she usually has to pin the pattern in place to cut the fabric. The pins damage the pattern and can warp delicate fabrics. Pattern weights are simply small, heavy objects that can hold the pattern in place without pins.
The number and size of the weights depends on the size of the pattern. On a pattern piece for clothing I would spread 4 weights, on something small like a plushy maybe 1 weight is enough. For small patterns the weight must be small enough to fit entirely inside the pattern and not overlap with the outlines.
Pattern weights come in all shapes and sizes and you can make your own from heavy objects like washers, stones, metal bolts or other junk you find lying around. You can google around for various ideas on how to craft your own pattern weights.
Thread clipper
These small tools are basically "just small scissors" intended to cut individual threads. They are very comfortable to use and - in contrast to regular scissors - you can hold them in your hand while hand sewing or stitching without being afraid of accidently cutting something.
I personally love them and prefer them above regular small scissors for hand and machine sewing.
Thread rack
This can be a lovely DIY project for you, but the result will only be useful if she needs lots of thread spools (mostly in different colors).
A thread rack allows you to order your thread spools and store them in a vertical manner, leaving more desk space for the important work. You can google around to find different models and instructions to build one yourself, and you can buy them, too. Make sure the size of the rack fits the size of thread spools your wife uses.
High quality pins
If she just started her business, she might not notice the difference yet, but cheap, low quality pins have the tendency to snag the fabric, either because they weren't manufactured cleanly or because the smoth outer coat corrodes over time.
Long, lean pins tend to be more practical than shorter or thicker ones. They should have a pinhead that's big enough to be easiy seen but not so big as to get into your way.
Hand sewing needles and thread conditioner
If she does some hand sewing, she needs hand sewing needles. I made the very unfortunate experience that those needle packs that are highly availyble in big super markets often have sharp points on their rear end, which hurts and can actually injure your fingers.
Good quality needles should be very smooth and shiny. They will corode somewhat over time and get dull (not only the tip, but also the body surface), which is when they need to be replaced because they don't glide through the fabric anymore. Find the dullest (dark and least shiny) needles in your wifes pin cushion and you'll know the size she needs most.
Another supply only needed for hand sewing is beeswax or thread conditioner. It's mostly used when sewing with natural fibres and I only know it from historical costuming (hand sewing with linen thread). One small block of beeswax or pack of conditioner lasts an eternity, but it can be very bothersome to get a replacement if you lost it or actually used it up.
Fabric clips
This is an alternative to pins. They look a little like miniature clothepins and can hold layers of fabric together without damaging the fabric.
Some people prefer clips, others prefer regular pins. In my experience there will always be some situations where you must use a pin because you simply cannot attach a clip there.
Sewing machine bobbins
This might not be obvious at first glance and might not be useful at all if she always sews with the same color of thread.
Every sewing machine needs 2 threads and the second thread must be wound up on a bobbin. If your wife has many different colors of thread and needs to change colors regularily, she also has to change the bobbin or (in the worst case) unwind a bobbin and fill it with a thread of a different color.
A stash of empty bobbins can help tremendously in that case. Unfortunately there is no one standardized size of bobbin, so you better take one of her existing bobbins and find a package of the same size and material.
A decent working table
Again, this depends on what she usually makes. I hate working on a surface that can't accomodate the entire pattern and still has some more room for excess fabric. If she makes small things, a regular desk can be more than enough, but if she tailors clothing, she needs something bigger.
