Two reactions with nicotine: 1) no issues worth any discussion or 2) nausea, what I call the "Copenhagen buzz", skin irritation, or some more minor symptoms.

I recall as a 10 year on on my initiation to manhood (so described by an older buddy) that it had no negative effect on me, except the buzz (this was a very mild old brand), but two others had issues. One turned green and started vomiting the other was "high" and he was light headed. The average "dip" of Copenhagen (the strongest of the brands) is 11 to 12.8 mg nicotine.

The responses I hear in my family are the same as listed.

Nicotine is in much lower quantities in tomato (firm green, not ripe, nicotine protects the fruit from pathogens and insects), potato (dispersed throughout, although I would avoid eating the carbohydrates as they convert to sugar and which both are inflamatory...bad for you), pepper (eat all you can, mild to hot, hotter is better as it had more capsaicin and vitamin C), eggplant, and some spices in that family, and outside that family of plants (Solanaceae) cellery and cauliflower.
These are really "bioavailable".

If you use gum, try the 2 mg. Just break the surface of the gum a bit with your teeth and put it in your cheek or under your tongue for direct absorption into your blood stream. Each five to ten minutes you need to slightly chew the gum and then put it back in the cheek or under the tongue. It will take a number of times to render all the nicotine. This method prevents the nicotine from getting into your stomach.

A 3 mg pouch of Zyn or similar product causes less mouth watering and more direct absorbtion and you can choose flavors.

Cost per mg of nicotine is the least in the pouches. Zyn can be purchased at a large discount if bought in volume on the website.
Walmart or similar chain is the least expensive. In volume, it is less than $4 per "can". The site we used was Northerner.

Just worth mentioning, I dipped Copenhagen or other brands for 36 years. I had the flu only twice in that time and rarely had anything else my siblinngs or parents had or later in my own wife and children. The insurance company made me quit. I notice my buddies that still dip today have had little or no Covid. This is now supported by several published research papers this year on nicotine and Covid or long Covid.

Each person had to "find" the dosage which works for them. The suggested dosages had little or no effect on me. I had to dose and wait for response for about three weeks until I found my rate. Then the effect was extremely significant. All my long Covid symptoms went away after about 15 days of treatment on the correct dose for my body. I expect the response is dependent on a) other nicotine intake (we eat a good bit of cauliflower, cellery, peppers, and tomatoes), b) individual metabolism, c) body weight, and d) the level the body is impacted by Covid or long Covid.

My cases of Covid and long Covid have been bad to severe.

I believe the nicotine, from my response and my familes (daughters, son-in-law), wife, and others I communicate with is a game changer. The published research shows that the nicotine blocks some cell receptor sites and modulates cytokinin (cause for cytokinin storm in the body which is an over reaction to the virus from our immune systems).

Nicotine and addiction? Well, are you addicted to peppers, tomato, egglant, cellery, cauliflower, or potatoes?

Our cells have nicotine receptors. Nicotine is in some of the "healthiest" vegetables. Nicotine protects the fruit from disease and insects. Nicotine is a minor plant alkaloid. Other plant alkaloids include caffeine, vincristine, emitine (life saving drug), and others.

Nicotine can be toxic if high levels are taken. Read up on this by searching the word string: nicotine, Covid, toxicity, alkaloid, and dosage.